diff --git a/Controllers/WorkshopsController.cs b/Controllers/WorkshopsController.cs
index aaee027..8b37c04 100644
--- a/Controllers/WorkshopsController.cs
+++ b/Controllers/WorkshopsController.cs
@@ -16,25 +16,198 @@ public class WorkshopsController : ControllerBase
 
     /// <summary>Lista workshops com filtros opcionais.</summary>
     [HttpGet]
-    public Task<IActionResult> GetAll([FromQuery] DateTimeOffset? from, [FromQuery] DateTimeOffset? to, [FromQuery] string? q, CancellationToken ct)
+    public async Task<IActionResult> GetAll([FromQuery] DateTimeOffset? from, [FromQuery] DateTimeOffset? to, [FromQuery] string? q, CancellationToken ct)
     {
-        // TODO: implementar usando _repo.GetAllAsync e mapear para WorkshopResponse
-        return Task.FromResult<IActionResult>(Ok(Array.Empty<WorkshopResponse>()));
+        var workshops = await _repo.GetAllAsync(from, to, q, ct);
+        
+        var response = workshops.Select(w => new WorkshopResponse(
+            w.Id,
+            w.Title,
+            w.Description,
+            w.StartAt,
+            w.EndAt,
+            w.Location,
+            w.Capacity,
+            w.IsOnline
+        )).ToList();
+
+        return Ok(response);
     }
 
     /// <summary>Obtém um workshop por Id.</summary>
     [HttpGet("{id:guid}")]
-    public Task<IActionResult> GetById(Guid id, CancellationToken ct)
+    public async Task<IActionResult> GetById(Guid id, CancellationToken ct)
     {
-        // TODO: implementar usando _repo.GetByIdAsync
-        return Task.FromResult<IActionResult>(NotFound());
+        var workshop = await _repo.GetByIdAsync(id, ct);
+        
+        if (workshop == null)
+        {
+            return NotFound();
+        }
+
+        var response = new WorkshopResponse(
+            workshop.Id,
+            workshop.Title,
+            workshop.Description,
+            workshop.StartAt,
+            workshop.EndAt,
+            workshop.Location,
+            workshop.Capacity,
+            workshop.IsOnline
+        );
+
+        return Ok(response);
     }
 
     /// <summary>Cria um novo workshop.</summary>
     [HttpPost]
-    public Task<IActionResult> Create([FromBody] CreateWorkshopRequest body, CancellationToken ct)
+    public async Task<IActionResult> Create([FromBody] CreateWorkshopRequest body, CancellationToken ct)
     {
-        // TODO: validar ModelState, regras de negócio e chamar _repo.AddAsync; retornar CreatedAtAction
-        return Task.FromResult<IActionResult>(BadRequest());
+        if (!ModelState.IsValid)
+        {
+            return BadRequest(ModelState);
+        }
+
+        // Validações de negócio
+        if (body.StartAt >= body.EndAt)
+        {
+            return BadRequest("Data de início deve ser anterior à data de fim.");
+        }
+
+        if (body.StartAt < DateTimeOffset.UtcNow)
+        {
+            return BadRequest("Data de início deve ser no futuro.");
+        }
+
+        if (!body.IsOnline && string.IsNullOrWhiteSpace(body.Location))
+        {
+            return BadRequest("Location é obrigatório para workshops presenciais.");
+        }
+
+        if (body.Capacity < 1)
+        {
+            return BadRequest("Capacidade deve ser pelo menos 1.");
+        }
+
+        var workshop = new Workshop
+        {
+            Id = Guid.NewGuid(),
+            Title = body.Title,
+            Description = body.Description,
+            StartAt = body.StartAt,
+            EndAt = body.EndAt,
+            Location = body.Location,
+            Capacity = body.Capacity,
+            IsOnline = body.IsOnline
+        };
+
+        var createdWorkshop = await _repo.AddAsync(workshop, ct);
+
+        var response = new WorkshopResponse(
+            createdWorkshop.Id,
+            createdWorkshop.Title,
+            createdWorkshop.Description,
+            createdWorkshop.StartAt,
+            createdWorkshop.EndAt,
+            createdWorkshop.Location,
+            createdWorkshop.Capacity,
+            createdWorkshop.IsOnline
+        );
+
+        return CreatedAtAction(nameof(GetById), new { id = createdWorkshop.Id }, response);
+    }
+
+    /// <summary>Atualiza parcialmente um workshop existente.</summary>
+    [HttpPatch("{id:guid}")]
+    public async Task<IActionResult> Patch(Guid id, [FromBody] PatchWorkshopRequest body, CancellationToken ct)
+    {
+        if (!ModelState.IsValid)
+        {
+            return BadRequest(ModelState);
+        }
+
+        var existingWorkshop = await _repo.GetByIdAsync(id, ct);
+        if (existingWorkshop == null)
+        {
+            return NotFound();
+        }
+
+        // Aplicar apenas os campos fornecidos
+        if (body.Title != null)
+            existingWorkshop.Title = body.Title;
+        
+        if (body.Description != null)
+            existingWorkshop.Description = body.Description;
+        
+        if (body.StartAt.HasValue)
+        {
+            if (body.StartAt.Value < DateTimeOffset.UtcNow)
+            {
+                return BadRequest("Data de início deve ser no futuro.");
+            }
+            existingWorkshop.StartAt = body.StartAt.Value;
+        }
+        
+        if (body.EndAt.HasValue)
+            existingWorkshop.EndAt = body.EndAt.Value;
+        
+        if (body.Location != null)
+            existingWorkshop.Location = body.Location;
+        
+        if (body.Capacity.HasValue)
+        {
+            if (body.Capacity.Value < 1)
+            {
+                return BadRequest("Capacidade deve ser pelo menos 1.");
+            }
+            existingWorkshop.Capacity = body.Capacity.Value;
+        }
+        
+        if (body.IsOnline.HasValue)
+            existingWorkshop.IsOnline = body.IsOnline.Value;
+
+        // Validações de negócio após aplicar mudanças
+        if (existingWorkshop.StartAt >= existingWorkshop.EndAt)
+        {
+            return BadRequest("Data de início deve ser anterior à data de fim.");
+        }
+
+        if (!existingWorkshop.IsOnline && string.IsNullOrWhiteSpace(existingWorkshop.Location))
+        {
+            return BadRequest("Location é obrigatório para workshops presenciais.");
+        }
+
+        var updatedWorkshop = await _repo.UpdateAsync(existingWorkshop, ct);
+        if (updatedWorkshop == null)
+        {
+            return NotFound();
+        }
+
+        var response = new WorkshopResponse(
+            updatedWorkshop.Id,
+            updatedWorkshop.Title,
+            updatedWorkshop.Description,
+            updatedWorkshop.StartAt,
+            updatedWorkshop.EndAt,
+            updatedWorkshop.Location,
+            updatedWorkshop.Capacity,
+            updatedWorkshop.IsOnline
+        );
+
+        return Ok(response);
+    }
+
+    /// <summary>Remove um workshop.</summary>
+    [HttpDelete("{id:guid}")]
+    public async Task<IActionResult> Delete(Guid id, CancellationToken ct)
+    {
+        var workshop = await _repo.GetByIdAsync(id, ct);
+        if (workshop == null)
+        {
+            return NotFound();
+        }
+
+        await _repo.DeleteAsync(id, ct);
+        return NoContent();
     }
 }
diff --git a/Dtos/CreateWorkshopRequest.cs b/Dtos/CreateWorkshopRequest.cs
index 7686335..86cd69d 100644
--- a/Dtos/CreateWorkshopRequest.cs
+++ b/Dtos/CreateWorkshopRequest.cs
@@ -1,13 +1,28 @@
 
+using System.ComponentModel.DataAnnotations;
+
 namespace CampusWorkshops.Api.Dtos;
 
-// DTO para criação de Workshop.
+// DTO para criação de Workshop com validações
 public record CreateWorkshopRequest(
-    string? Title,
+    [Required(ErrorMessage = "Título é obrigatório")]
+    [StringLength(120, MinimumLength = 3, ErrorMessage = "Título deve ter entre 3 e 120 caracteres")]
+    string Title,
+    
+    [StringLength(2000, ErrorMessage = "Descrição não pode exceder 2000 caracteres")]
     string? Description,
+    
+    [Required(ErrorMessage = "Data de início é obrigatória")]
     DateTimeOffset StartAt,
+    
+    [Required(ErrorMessage = "Data de fim é obrigatória")]
     DateTimeOffset EndAt,
+    
+    [StringLength(200, ErrorMessage = "Localização não pode exceder 200 caracteres")]
     string? Location,
+    
+    [Range(1, 1000, ErrorMessage = "Capacidade deve estar entre 1 e 1000")]
     int Capacity,
+    
     bool IsOnline
 );
diff --git a/Dtos/PatchWorkshopRequest.cs b/Dtos/PatchWorkshopRequest.cs
new file mode 100644
index 0000000..d1be497
--- /dev/null
+++ b/Dtos/PatchWorkshopRequest.cs
@@ -0,0 +1,23 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace CampusWorkshops.Api.Dtos;
+
+// DTO para atualização parcial de Workshop.
+public record PatchWorkshopRequest(
+    [StringLength(120, MinimumLength = 3, ErrorMessage = "Título deve ter entre 3 e 120 caracteres")]
+    string? Title,
+    
+    [StringLength(2000, ErrorMessage = "Descrição não pode exceder 2000 caracteres")]
+    string? Description,
+    
+    DateTimeOffset? StartAt,
+    DateTimeOffset? EndAt,
+    
+    [StringLength(200, ErrorMessage = "Localização não pode exceder 200 caracteres")]
+    string? Location,
+    
+    [Range(1, 1000, ErrorMessage = "Capacidade deve estar entre 1 e 1000")]
+    int? Capacity,
+    
+    bool? IsOnline
+);
diff --git a/Models/Workshop.cs b/Models/Workshop.cs
index 64a19d2..4f3816d 100644
--- a/Models/Workshop.cs
+++ b/Models/Workshop.cs
@@ -1,28 +1,32 @@
 
+using System.ComponentModel.DataAnnotations;
+
 namespace CampusWorkshops.Api.Models;
 
-// Modelo mínimo para Workshop.Completar as validações
-// e ajustar os tipos/atributos durante a atividade.
+// Modelo mínimo para Workshop com validações
 public class Workshop
 {
     // Identificador único
     public Guid Id { get; set; } = Guid.NewGuid();
 
-    // TODO: adicionar [Required], [StringLength(120, MinimumLength = 3)]
+    [Required(ErrorMessage = "Título é obrigatório")]
+    [StringLength(120, MinimumLength = 3, ErrorMessage = "Título deve ter entre 3 e 120 caracteres")]
     public string? Title { get; set; }
 
-    // TODO: limitar tamanho (ex.: 2000)
+    [StringLength(2000, ErrorMessage = "Descrição não pode exceder 2000 caracteres")]
     public string? Description { get; set; }
 
-    // TODO: usar DateTimeOffset com formato ISO 8601
+    [Required(ErrorMessage = "Data de início é obrigatória")]
     public DateTimeOffset StartAt { get; set; }
 
+    [Required(ErrorMessage = "Data de fim é obrigatória")]
     public DateTimeOffset EndAt { get; set; }
 
-    // Location deve ser obrigatório se IsOnline == false
+    // Location deve ser obrigatório se IsOnline == false (validado no controller)
+    [StringLength(200, ErrorMessage = "Localização não pode exceder 200 caracteres")]
     public string? Location { get; set; }
 
-    // TODO: validar Capacity >= 1
+    [Range(1, 1000, ErrorMessage = "Capacidade deve estar entre 1 e 1000")]
     public int Capacity { get; set; } = 1;
 
     public bool IsOnline { get; set; }
diff --git a/Program.cs b/Program.cs
index 29f9166..7fa8063 100644
--- a/Program.cs
+++ b/Program.cs
@@ -1,10 +1,12 @@
 // Note: repository implementation removed for workshop exercise (TODOs in project files)
 using Microsoft.AspNetCore.Diagnostics;
 using Microsoft.AspNetCore.Mvc;
+using CampusWorkshops.Api.Repositories;
 
 var builder = WebApplication.CreateBuilder(args);
 
 // Add services
+builder.Services.AddSingleton<IWorkshopRepository, InMemoryWorkshopRepository>();
 builder.Services.AddControllers();
 builder.Services.AddEndpointsApiExplorer();
 builder.Services.AddSwaggerGen(o =>
diff --git a/Repositories/IWorkshopRepository.cs b/Repositories/IWorkshopRepository.cs
index ff8bfda..e36013f 100644
--- a/Repositories/IWorkshopRepository.cs
+++ b/Repositories/IWorkshopRepository.cs
@@ -9,4 +9,8 @@ public interface IWorkshopRepository
     Task<IReadOnlyList<Workshop>> GetAllAsync(DateTimeOffset? from, DateTimeOffset? to, string? q, CancellationToken ct);
     Task<Workshop?> GetByIdAsync(Guid id, CancellationToken ct);
     Task<Workshop> AddAsync(Workshop workshop, CancellationToken ct);
+    Task<Workshop?> UpdateAsync(Workshop workshop, CancellationToken ct);
+    Task<bool> DeleteAsync(Guid id, CancellationToken ct);
+    Task<bool> ExistsAsync(Guid id, CancellationToken ct);
+    Task<Workshop?> UpdatePartialAsync(Guid id, Action<Workshop> updateAction, CancellationToken ct);
 }
diff --git a/Repositories/InMemoryWorkshopRepository.cs b/Repositories/InMemoryWorkshopRepository.cs
index e887e44..cc831fc 100644
--- a/Repositories/InMemoryWorkshopRepository.cs
+++ b/Repositories/InMemoryWorkshopRepository.cs
@@ -6,26 +6,215 @@ namespace CampusWorkshops.Api.Repositories;
 // In-memory repository stub
 public class InMemoryWorkshopRepository : IWorkshopRepository
 {
+    List<Workshop> _workshops = new();
+
+    private void Seed()
+    {
+        // Base de datas: sempre a partir da próxima semana, para não “envelhecer” o seed
+        var baseDate = DateTimeOffset.UtcNow.Date.AddDays(7);
+
+        var w1 = new Workshop
+        {
+            Id = Guid.Parse("8a0b9f1b-6c9b-4a2a-9d5e-1c2f3a4b5c6d"),
+            Title = "APIs RESTful — visão geral",
+            Description = "Modelagem de recursos, status codes e boas práticas.",
+            StartAt = baseDate.AddHours(12),   // daqui a 7 dias, 12:00 UTC
+            EndAt   = baseDate.AddHours(15),   // 15:00 UTC
+            Location = "Lab 101",
+            Capacity = 25,
+            IsOnline = false
+        };
+
+        var w2 = new Workshop
+        {
+            Id = Guid.Parse("1c3d5e7f-9a2b-4c6d-8e0f-1a2b3c4d5e6f"),
+            Title = "Entity Framework — mapeamentos e LINQ",
+            Description = "Relações, consultas eficientes e boas práticas.",
+            StartAt = baseDate.AddDays(2).AddHours(12), // +2 dias, 12:00 UTC
+            EndAt   = baseDate.AddDays(2).AddHours(14), // 14:00 UTC
+            Location = null,   // online
+            Capacity = 40,
+            IsOnline = true
+        };
+
+        var w3 = new Workshop
+        {
+            Id = Guid.Parse("f0e1d2c3-b4a5-6789-9a8b-7c6d5e4f3a2b"),
+            Title = "Construindo contratos com Swagger/OpenAPI",
+            Description = "Documentação viva, exemplos e testes via Swagger UI.",
+            StartAt = baseDate.AddDays(5).AddHours(13), // +5 dias, 13:00 UTC
+            EndAt   = baseDate.AddDays(5).AddHours(16), // 16:00 UTC
+            Location = "Auditório Central",
+            Capacity = 80,
+            IsOnline = false
+        };
+
+        _workshops.Add(w1);
+        _workshops.Add(w2);
+        _workshops.Add(w3);
+    }
+
+
     public InMemoryWorkshopRepository()
     {
-        // TODO: Adicionar workshops iniciais 
+        Seed();
     }
 
     public Task<IReadOnlyList<Workshop>> GetAllAsync(DateTimeOffset? from, DateTimeOffset? to, string? q, CancellationToken ct)
     {
-        // TODO: retornar uma lista filtrada e ordenada por StartAt
-        return Task.FromResult<IReadOnlyList<Workshop>>(Array.Empty<Workshop>());
+        var query = _workshops.AsQueryable();
+
+        // Filtro por data início (from)
+        if (from.HasValue)
+        {
+            query = query.Where(w => w.StartAt >= from.Value);
+        }
+
+        // Filtro por data fim (to)  
+        if (to.HasValue)
+        {
+            query = query.Where(w => w.StartAt <= to.Value);
+        }
+
+        // Filtro por texto (q) - busca no título e descrição
+        if (!string.IsNullOrWhiteSpace(q))
+        {
+            var searchTerm = q.Trim().ToLowerInvariant();
+            query = query.Where(w => 
+                (w.Title != null && w.Title.ToLowerInvariant().Contains(searchTerm)) ||
+                (w.Description != null && w.Description.ToLowerInvariant().Contains(searchTerm))
+            );
+        }
+
+        // Ordenar por data de início
+        var result = query.OrderBy(w => w.StartAt).ToList();
+        
+        return Task.FromResult<IReadOnlyList<Workshop>>(result);
     }
 
     public Task<Workshop?> GetByIdAsync(Guid id, CancellationToken ct)
     {
-        // TODO: buscar por id
-        return Task.FromResult<Workshop?>(null);
+        var workshop = _workshops.FirstOrDefault(w => w.Id == id);
+        return Task.FromResult(workshop);
     }
 
     public Task<Workshop> AddAsync(Workshop workshop, CancellationToken ct)
     {
-        // TODO: adicionar à lista em memória e retornar criado
+        // Gerar novo ID se não foi fornecido ou se já existe
+        if (workshop.Id == Guid.Empty || _workshops.Any(w => w.Id == workshop.Id))
+        {
+            workshop.Id = Guid.NewGuid();
+        }
+
+        // Validações de negócio que serão úteis quando migrar para banco
+        ValidateWorkshop(workshop);
+
+        _workshops.Add(workshop);
         return Task.FromResult(workshop);
     }
+
+    public Task<Workshop?> UpdateAsync(Workshop workshop, CancellationToken ct)
+    {
+        var existingIndex = _workshops.FindIndex(w => w.Id == workshop.Id);
+        if (existingIndex < 0)
+        {
+            return Task.FromResult<Workshop?>(null);
+        }
+
+        // Validações de negócio
+        ValidateWorkshop(workshop);
+
+        _workshops[existingIndex] = workshop;
+        return Task.FromResult<Workshop?>(workshop);
+    }
+
+    public Task<bool> DeleteAsync(Guid id, CancellationToken ct)
+    {
+        var workshop = _workshops.FirstOrDefault(w => w.Id == id);
+        if (workshop == null)
+        {
+            return Task.FromResult(false);
+        }
+
+        _workshops.Remove(workshop);
+        return Task.FromResult(true);
+    }
+
+    public Task<bool> ExistsAsync(Guid id, CancellationToken ct)
+    {
+        var exists = _workshops.Any(w => w.Id == id);
+        return Task.FromResult(exists);
+    }
+
+    public Task<Workshop?> UpdatePartialAsync(Guid id, Action<Workshop> updateAction, CancellationToken ct)
+    {
+        var workshop = _workshops.FirstOrDefault(w => w.Id == id);
+        if (workshop == null)
+        {
+            return Task.FromResult<Workshop?>(null);
+        }
+
+        // Aplicar as modificações
+        updateAction(workshop);
+
+        // Validar após modificações
+        ValidateWorkshop(workshop);
+
+        return Task.FromResult<Workshop?>(workshop);
+    }
+
+    private void ValidateWorkshop(Workshop workshop)
+    {
+        var errors = new List<string>();
+
+        // Validação de título
+        if (string.IsNullOrWhiteSpace(workshop.Title))
+        {
+            errors.Add("Title is required");
+        }
+        else if (workshop.Title.Length < 3 || workshop.Title.Length > 120)
+        {
+            errors.Add("Title must be between 3 and 120 characters");
+        }
+
+        // Validação de descrição
+        if (!string.IsNullOrWhiteSpace(workshop.Description) && workshop.Description.Length > 2000)
+        {
+            errors.Add("Description cannot exceed 2000 characters");
+        }
+
+        // Validação de datas
+        if (workshop.EndAt <= workshop.StartAt)
+        {
+            errors.Add("End date must be after start date");
+        }
+
+        if (workshop.StartAt <= DateTimeOffset.UtcNow)
+        {
+            errors.Add("Start date must be in the future");
+        }
+
+        // Validação de capacidade
+        if (workshop.Capacity < 1)
+        {
+            errors.Add("Capacity must be at least 1");
+        }
+
+        // Validação de localização para workshops presenciais
+        if (!workshop.IsOnline && string.IsNullOrWhiteSpace(workshop.Location))
+        {
+            errors.Add("Location is required for in-person workshops");
+        }
+
+        // Validação de localização para workshops online
+        if (workshop.IsOnline && !string.IsNullOrWhiteSpace(workshop.Location))
+        {
+            errors.Add("Location should not be specified for online workshops");
+        }
+
+        if (errors.Any())
+        {
+            throw new ArgumentException($"Workshop validation failed: {string.Join(", ", errors)}");
+        }
+    }
 }