diff --git a/SeaHaven.Services.Tests/PagedResultTests.cs b/SeaHaven.Services.Tests/PagedResultTests.cs
new file mode 100644
index 0000000..911370e
--- /dev/null
+++ b/SeaHaven.Services.Tests/PagedResultTests.cs
@@ -0,0 +1,34 @@
+using FluentAssertions;
+using SeaHaven.Services.DTOs;
+using Xunit;
+
+namespace SeaHaven.Services.Tests;
+
+public class PagedResultTests
+{
+    [Theory]
+    [InlineData(0, 10, 0)]
+    [InlineData(10, 10, 1)]
+    [InlineData(25, 10, 3)]
+    [InlineData(100, 25, 4)]
+    public void TotalPages_IsCeilingOfCountOverPageSize(int totalCount, int pageSize, int expectedPages)
+    {
+        var result = new PagedResult<string> { TotalCount = totalCount, PageSize = pageSize, Page = 1 };
+
+        result.TotalPages.Should().Be(expectedPages);
+    }
+
+    [Fact]
+    public void HasPrevious_IsFalseOnFirstPage_TrueAfterward()
+    {
+        new PagedResult<string> { Page = 1, PageSize = 10, TotalCount = 30 }.HasPrevious.Should().BeFalse();
+        new PagedResult<string> { Page = 2, PageSize = 10, TotalCount = 30 }.HasPrevious.Should().BeTrue();
+    }
+
+    [Fact]
+    public void HasNext_IsTrueBeforeLastPage_FalseOnLastPage()
+    {
+        new PagedResult<string> { Page = 2, PageSize = 10, TotalCount = 30 }.HasNext.Should().BeTrue();
+        new PagedResult<string> { Page = 3, PageSize = 10, TotalCount = 30 }.HasNext.Should().BeFalse();
+    }
+}
diff --git a/SeaHaven.Services.Tests/SeaHaven.Services.Tests.csproj b/SeaHaven.Services.Tests/SeaHaven.Services.Tests.csproj
new file mode 100644
index 0000000..fdbbfc2
--- /dev/null
+++ b/SeaHaven.Services.Tests/SeaHaven.Services.Tests.csproj
@@ -0,0 +1,23 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
+    <PackageReference Include="xunit" Version="2.9.2" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2" />
+    <PackageReference Include="FluentAssertions" Version="6.12.1" />
+    <PackageReference Include="FluentValidation" Version="12.1.1" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\SeaHaven.Services\SeaHaven.Services.csproj" />
+  </ItemGroup>
+
+</Project>
diff --git a/SeaHaven.Services.Tests/ValidationTests.cs b/SeaHaven.Services.Tests/ValidationTests.cs
new file mode 100644
index 0000000..5d682a9
--- /dev/null
+++ b/SeaHaven.Services.Tests/ValidationTests.cs
@@ -0,0 +1,104 @@
+using FluentAssertions;
+using SeaHaven.Services.DTOs;
+using SeaHaven.Services.Validation;
+using Xunit;
+
+namespace SeaHaven.Services.Tests;
+
+public class CreateAssetValidationTests
+{
+    private readonly CreateAssetValidation _validator = new();
+
+    [Fact]
+    public void Validate_WhenNameEmpty_Fails()
+    {
+        var result = _validator.Validate(new CreateAssetDTO { Name = "" });
+
+        result.IsValid.Should().BeFalse();
+        result.Errors.Should().Contain(e => e.PropertyName == nameof(CreateAssetDTO.Name));
+    }
+
+    [Fact]
+    public void Validate_WhenNameTooLong_Fails()
+    {
+        var result = _validator.Validate(new CreateAssetDTO { Name = new string('a', 201) });
+
+        result.IsValid.Should().BeFalse();
+        result.Errors.Should().Contain(e => e.PropertyName == nameof(CreateAssetDTO.Name));
+    }
+
+    [Fact]
+    public void Validate_WhenLocationIdZero_Fails()
+    {
+        var result = _validator.Validate(new CreateAssetDTO { Name = "Pump", LocationId = 0 });
+
+        result.IsValid.Should().BeFalse();
+        result.Errors.Should().Contain(e => e.PropertyName == nameof(CreateAssetDTO.LocationId));
+    }
+
+    [Fact]
+    public void Validate_WhenValid_Passes()
+    {
+        var result = _validator.Validate(new CreateAssetDTO { Name = "Pump", LocationId = 5 });
+
+        result.IsValid.Should().BeTrue();
+    }
+}
+
+public class CreateContactValidationTests
+{
+    private readonly CreateContactValidation _validator = new();
+
+    private static CreateContactDTO Valid() => new()
+    {
+        FirstName = "Ada",
+        LastName = "Lovelace",
+        Email = "ada@example.com"
+    };
+
+    [Fact]
+    public void Validate_WhenNamesMissing_Fails()
+    {
+        var dto = Valid();
+        dto.FirstName = "";
+        dto.LastName = "";
+
+        var result = _validator.Validate(dto);
+
+        result.IsValid.Should().BeFalse();
+        result.Errors.Should().Contain(e => e.PropertyName == nameof(CreateContactDTO.FirstName));
+        result.Errors.Should().Contain(e => e.PropertyName == nameof(CreateContactDTO.LastName));
+    }
+
+    [Fact]
+    public void Validate_WhenEmailMalformed_Fails()
+    {
+        var dto = Valid();
+        dto.Email = "not-an-email";
+
+        var result = _validator.Validate(dto);
+
+        result.IsValid.Should().BeFalse();
+        result.Errors.Should().Contain(e => e.PropertyName == nameof(CreateContactDTO.Email));
+    }
+
+    [Fact]
+    public void Validate_WhenPhoneTooLong_Fails()
+    {
+        var dto = Valid();
+        dto.Phone = new string('1', 21);
+
+        var result = _validator.Validate(dto);
+
+        result.IsValid.Should().BeFalse();
+        result.Errors.Should().Contain(e => e.PropertyName == nameof(CreateContactDTO.Phone));
+    }
+
+    [Fact]
+    public void Validate_WhenValid_Passes()
+    {
+        var result = _validator.Validate(Valid());
+
+        result.IsValid.Should().BeTrue();
+    }
+}
diff --git a/SeaHaven.Services.Tests/WorkOrderMappingTests.cs b/SeaHaven.Services.Tests/WorkOrderMappingTests.cs
new file mode 100644
index 0000000..28f6ea3
--- /dev/null
+++ b/SeaHaven.Services.Tests/WorkOrderMappingTests.cs
@@ -0,0 +1,74 @@
+using Data.SeaHavenIndustries;
+using Data.SeaHavenIndustries.Enums;
+using FluentAssertions;
+using SeaHaven.Services.DTOs;
+using Xunit;
+
+namespace SeaHaven.Services.Tests;
+
+public class WorkOrderMappingTests
+{
+    [Fact]
+    public void MapToModel_WithValidEnumStrings_ParsesStatusAndPriority()
+    {
+        var entity = new WorkOrder
+        {
+            Id = 7,
+            WorkerOrderTitle = "Fix pump",
+            Status = "InProgress",
+            Priority = "High"
+        };
+
+        var dto = WorkOrderDTO.MapToModel(entity);
+
+        dto.Id.Should().Be(7);
+        dto.WorkerOrderTitle.Should().Be("Fix pump");
+        dto.Status.Should().Be(WorkOrderStatus.InProgress);
+        dto.Priority.Should().Be(WorkOrderPriority.High);
+    }
+
+    [Fact]
+    public void MapToModel_WithUnparseableEnumStrings_FallsBackToDefaults()
+    {
+        var entity = new WorkOrder
+        {
+            WorkerOrderTitle = "Garbage",
+            Status = "not-a-status",
+            Priority = "not-a-priority"
+        };
+
+        var dto = WorkOrderDTO.MapToModel(entity);
+
+        dto.Status.Should().Be(WorkOrderStatus.Open);
+        dto.Priority.Should().Be(WorkOrderPriority.Medium);
+    }
+
+    [Fact]
+    public void MapToEntity_SerializesEnumsToStrings()
+    {
+        var dto = new WorkOrderDTO
+        {
+            Id = 3,
+            WorkerOrderTitle = "Inspect",
+            Status = WorkOrderStatus.Completed,
+            Priority = WorkOrderPriority.Critical
+        };
+
+        var entity = WorkOrderDTO.MapToEntity(dto);
+
+        entity.Status.Should().Be("Completed");
+        entity.Priority.Should().Be("Critical");
+    }
+
+    [Fact]
+    public void CreateMapToEntity_WhenStatusAndPriorityNull_AppliesDefaults()
+    {
+        var dto = new CreateWorkOrderDTO { WorkerOrderTitle = "New" };
+
+        var entity = CreateWorkOrderDTO.MapToEntity(dto);
+
+        entity.Status.Should().Be("Open");
+        entity.Priority.Should().Be("Medium");
+        entity.CreatedDate.Should().NotBeNull();
+    }
+}
diff --git a/SeaHavenIndustries.sln b/SeaHavenIndustries.sln
index b9df8e5..429aed6 100644
--- a/SeaHavenIndustries.sln
+++ b/SeaHavenIndustries.sln
@@ -15,6 +15,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SeaHaven.DataServices", "Se
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Api.SeaHavenIndustries.Tests", "Api.SeaHavenIndustries.Tests\Api.SeaHavenIndustries.Tests.csproj", "{1222E2E5-2FB0-4AA8-842C-0D77CFBA5E45}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SeaHaven.Services.Tests", "SeaHaven.Services.Tests\SeaHaven.Services.Tests.csproj", "{97455198-C479-47F2-8BC8-601B335DFFAB}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -45,6 +47,10 @@ Global
 		{1222E2E5-2FB0-4AA8-842C-0D77CFBA5E45}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{1222E2E5-2FB0-4AA8-842C-0D77CFBA5E45}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{1222E2E5-2FB0-4AA8-842C-0D77CFBA5E45}.Release|Any CPU.Build.0 = Release|Any CPU
+		{97455198-C479-47F2-8BC8-601B335DFFAB}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{97455198-C479-47F2-8BC8-601B335DFFAB}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{97455198-C479-47F2-8BC8-601B335DFFAB}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{97455198-C479-47F2-8BC8-601B335DFFAB}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE