diff --git a/ServiceScan.SourceGenerator.Tests/AddServicesTests.cs b/ServiceScan.SourceGenerator.Tests/AddServicesTests.cs
index 9208a71..17e8cff 100644
--- a/ServiceScan.SourceGenerator.Tests/AddServicesTests.cs
+++ b/ServiceScan.SourceGenerator.Tests/AddServicesTests.cs
@@ -59,6 +59,48 @@ public void AddServicesFromAnotherAssembly()
         Assert.Equal(Sources.GetMethodImplementation(registrations), results.GeneratedTrees[1].ToString());
     }
 
+    [Fact]
+    public void AddServicesFromReferencedCompilationsByDefault()
+    {
+        var coreCompilation = CreateCompilation(
+            """
+            namespace Core;
+            public interface IService { }
+            """)
+            .WithAssemblyName("Core");
+
+        var implementation1Compilation = CreateCompilation(["""
+            namespace Module1;
+            public class MyService1 : Core.IService { }
+            """],
+            [coreCompilation])
+            .WithAssemblyName("Module1");
+
+        var implementation2Compilation = CreateCompilation(["""
+            namespace Module2;
+            public class MyService2 : Core.IService { }
+            """],
+            [coreCompilation])
+            .WithAssemblyName("Module2");
+
+        var attribute = $"[GenerateServiceRegistrations(AssignableTo = typeof(Core.IService), Lifetime = ServiceLifetime.Scoped)]";
+        var registrationsCompilation = CreateCompilation(
+            [Sources.MethodWithAttribute(attribute)],
+            [coreCompilation, implementation1Compilation, implementation2Compilation]);
+
+        var results = CSharpGeneratorDriver
+            .Create(_generator)
+            .RunGenerators(registrationsCompilation)
+            .GetRunResult();
+
+        var registrations = $"""
+            return services
+                .AddScoped<global::Core.IService, global::Module1.MyService1>()
+                .AddScoped<global::Core.IService, global::Module2.MyService2>();
+            """;
+        Assert.Equal(Sources.GetMethodImplementation(registrations), results.GeneratedTrees[1].ToString());
+    }
+
     [Fact]
     public void AddServiceWithNonDirectInterface()
     {
@@ -990,20 +1032,29 @@ public void DontGenerateAnythingIfTypeIsInvalid()
     }
 
     private static Compilation CreateCompilation(params string[] source)
+    {
+        return CreateCompilation(source, []);
+    }
+
+    private static Compilation CreateCompilation(string[] source, Compilation[] referencedCompilations)
     {
         var path = Path.GetDirectoryName(typeof(object).Assembly.Location)!;
         var runtimeAssemblyPath = Path.Combine(path, "System.Runtime.dll");
 
         var runtimeReference = MetadataReference.CreateFromFile(typeof(object).Assembly.Location);
 
-        return CSharpCompilation.Create("compilation",
-                source.Select(s => CSharpSyntaxTree.ParseText(s)),
-                [
+        var metadataReferences = new MetadataReference[]
+            {
                     MetadataReference.CreateFromFile(typeof(object).Assembly.Location),
                     MetadataReference.CreateFromFile(runtimeAssemblyPath),
                     MetadataReference.CreateFromFile(typeof(IServiceCollection).Assembly.Location),
-                    MetadataReference.CreateFromFile(typeof(External.IExternalService).Assembly.Location),
-                ],
+                    MetadataReference.CreateFromFile(typeof(External.IExternalService).Assembly.Location)
+            }
+            .Concat(referencedCompilations.Select(c => c.ToMetadataReference()));
+
+        return CSharpCompilation.Create("compilation",
+                source.Select(s => CSharpSyntaxTree.ParseText(s)),
+                metadataReferences,
                 new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary));
     }
 }
diff --git a/ServiceScan.SourceGenerator/DependencyInjectionGenerator.FilterTypes.cs b/ServiceScan.SourceGenerator/DependencyInjectionGenerator.FilterTypes.cs
index a8ba52a..defef0b 100644
--- a/ServiceScan.SourceGenerator/DependencyInjectionGenerator.FilterTypes.cs
+++ b/ServiceScan.SourceGenerator/DependencyInjectionGenerator.FilterTypes.cs
@@ -15,8 +15,10 @@ public partial class DependencyInjectionGenerator
         var assemblyOfType = attribute.AssemblyOfTypeName is null
             ? null
             : compilation.GetTypeByMetadataName(attribute.AssemblyOfTypeName);
-        
-        var assembly = (assemblyOfType ?? containingType).ContainingAssembly;
+
+        var assemblies = assemblyOfType is not null
+            ? [assemblyOfType.ContainingAssembly]
+            : GetSolutionAssemblies(compilation);
 
         var assignableToType = attribute.AssignableToTypeName is null
             ? null
@@ -49,7 +51,7 @@ public partial class DependencyInjectionGenerator
             excludeAssignableToType = excludeAssignableToType.Construct(typeArguments);
         }
 
-        foreach (var type in GetTypesFromAssembly(assembly))
+        foreach (var type in assemblies.SelectMany(GetTypesFromAssembly))
         {
             if (type.IsAbstract || type.IsStatic || !type.CanBeReferencedByName || type.TypeKind != TypeKind.Class)
                 continue;
@@ -71,7 +73,7 @@ public partial class DependencyInjectionGenerator
 
             if (excludeByTypeNameRegex != null && excludeByTypeNameRegex.IsMatch(type.ToDisplayString()))
                 continue;
-            
+
             if (excludeAssignableToType != null && IsAssignableTo(type, excludeAssignableToType, out _))
                 continue;
 
@@ -137,6 +139,19 @@ private static bool IsAssignableTo(INamedTypeSymbol type, INamedTypeSymbol assig
         return false;
     }
 
+    private static IEnumerable<IAssemblySymbol> GetSolutionAssemblies(Compilation compilation)
+    {
+        yield return compilation.Assembly;
+
+        foreach (var reference in compilation.References)
+        {
+            if (reference is CompilationReference)
+            {
+                yield return (IAssemblySymbol)compilation.GetAssemblyOrModuleSymbol(reference);
+            }
+        }
+    }
+
     private static IEnumerable<INamedTypeSymbol> GetTypesFromAssembly(IAssemblySymbol assemblySymbol)
     {
         var @namespace = assemblySymbol.GlobalNamespace;