diff --git a/Sources/ProjectSpec/SpecValidation.swift b/Sources/ProjectSpec/SpecValidation.swift
index 376c0153f..1376aa724 100644
--- a/Sources/ProjectSpec/SpecValidation.swift
+++ b/Sources/ProjectSpec/SpecValidation.swift
@@ -147,7 +147,8 @@ extension Project {
 
         for target in aggregateTargets {
             for dependency in target.targets {
-                if getProjectTarget(dependency) == nil {
+                if getProjectTarget(dependency) == nil, let projectName = dependency.components(separatedBy: "/").first,
+                   (getPackage(projectName) == nil && getProjectReference(projectName) == nil) {
                     errors.append(.invalidTargetDependency(target: target.name, dependency: dependency))
                 }
             }
diff --git a/Sources/XcodeGenKit/PBXProjGenerator.swift b/Sources/XcodeGenKit/PBXProjGenerator.swift
index 60ebdfca3..927ddbfc0 100644
--- a/Sources/XcodeGenKit/PBXProjGenerator.swift
+++ b/Sources/XcodeGenKit/PBXProjGenerator.swift
@@ -336,7 +336,33 @@ public class PBXProjGenerator {
             return addObject(buildConfig)
         }
 
-        let dependencies = target.targets.map { generateTargetDependency(from: target.name, to: $0, platform: nil) }
+        let dependencies: [PBXTargetDependency] = target.targets.map {
+            let dependency = $0
+            if dependency.contains("/") && dependency.components(separatedBy: "/").count == 2 {
+                let tokens: [String] = dependency.components(separatedBy: "/")
+                let projectName: String = tokens[0]
+                let targetName: String = tokens[1]
+                
+                if nil != project.packages[projectName] {
+                    let productName = targetName
+                    let packageDependency = addObject(
+                        XCSwiftPackageProductDependency(productName: productName)
+                    )
+                    
+                    let targetDependency = addObject(
+                        PBXTargetDependency( product: packageDependency)
+                    )
+                    return targetDependency
+                }
+                
+                do {
+                    return try generateExternalTargetDependency(from: target.name, to: targetName, in: projectName, platform: .iOS).0
+                } catch {
+                    print("Error: \(error)")
+                }
+            }
+            return generateTargetDependency(from: target.name, to: $0, platform: nil)
+        }
 
         let defaultConfigurationName = project.options.defaultConfig ?? project.configs.first?.name ?? ""
         let buildConfigList = addObject(XCConfigurationList(
diff --git a/Tests/Fixtures/paths_test/included_paths_test.yml b/Tests/Fixtures/paths_test/included_paths_test.yml
index f40bf5aed..4606b7063 100644
--- a/Tests/Fixtures/paths_test/included_paths_test.yml
+++ b/Tests/Fixtures/paths_test/included_paths_test.yml
@@ -32,6 +32,7 @@ aggregateTargets:
   IncludedAggregateTarget:
     targets:
       - IncludedTarget
+      - AnotherProject/ExternalTarget
     configFiles:
       Config: config
     buildScripts:
diff --git a/Tests/ProjectSpecTests/SpecLoadingTests.swift b/Tests/ProjectSpecTests/SpecLoadingTests.swift
index 0c9c96657..380f842f7 100644
--- a/Tests/ProjectSpecTests/SpecLoadingTests.swift
+++ b/Tests/ProjectSpecTests/SpecLoadingTests.swift
@@ -97,7 +97,7 @@ class SpecLoadingTests: XCTestCase {
                 try expect(project.aggregateTargets) == [
                     AggregateTarget(
                         name: "IncludedAggregateTarget",
-                        targets: ["IncludedTarget"],
+                        targets: ["IncludedTarget", "AnotherProject/ExternalTarget"],
                         configFiles: ["Config": "paths_test/config"],
                         buildScripts: [BuildScript(script: .path("paths_test/buildScript"))]
                     ),
diff --git a/Tests/XcodeGenKitTests/ProjectGeneratorTests.swift b/Tests/XcodeGenKitTests/ProjectGeneratorTests.swift
index 4ed5ae082..72fa201d4 100644
--- a/Tests/XcodeGenKitTests/ProjectGeneratorTests.swift
+++ b/Tests/XcodeGenKitTests/ProjectGeneratorTests.swift
@@ -243,12 +243,21 @@ class ProjectGeneratorTests: XCTestCase {
 
     func testAggregateTargets() {
         describe {
-
+            let externalProjectPath = fixturePath + "TestProject/AnotherProject/AnotherProject.xcodeproj"
+            let projectReference1 = ProjectReference(name: "AnotherProject", path: externalProjectPath.string)
+            
+            var target = app
+            target.dependencies = [
+                Dependency(type: .target, reference: "AnotherProject/ExternalTarget")
+            ]
+            
             let otherTarget = Target(name: "Other", type: .framework, platform: .iOS, dependencies: [Dependency(type: .target, reference: "AggregateTarget")])
             let otherTarget2 = Target(name: "Other2", type: .framework, platform: .iOS, dependencies: [Dependency(type: .target, reference: "Other")], transitivelyLinkDependencies: true)
-            let aggregateTarget = AggregateTarget(name: "AggregateTarget", targets: ["MyApp", "MyFramework"])
+            let aggregateTarget = AggregateTarget(name: "AggregateTarget", targets: ["MyApp", "MyFramework", "AnotherProject/ExternalTarget"])
             let aggregateTarget2 = AggregateTarget(name: "AggregateTarget2", targets: ["AggregateTarget"])
-            let project = Project(name: "test", targets: [app, framework, otherTarget, otherTarget2], aggregateTargets: [aggregateTarget, aggregateTarget2])
+            
+            let project = Project(name: "test", targets: [target, framework, otherTarget, otherTarget2], aggregateTargets: [aggregateTarget, aggregateTarget2], projectReferences: [projectReference1])
+            
 
             $0.it("generates aggregate targets") {
                 let pbxProject = try project.generatePbxProj()
@@ -259,7 +268,7 @@ class ProjectGeneratorTests: XCTestCase {
                 try expect(aggregateTargets.count) == 2
 
                 let aggregateTarget1 = aggregateTargets.first { $0.name == "AggregateTarget" }
-                try expect(aggregateTarget1?.dependencies.count) == 2
+                try expect(aggregateTarget1?.dependencies.count) == 3
 
                 let aggregateTarget2 = aggregateTargets.first { $0.name == "AggregateTarget2" }
                 try expect(aggregateTarget2?.dependencies.count) == 1
@@ -270,7 +279,7 @@ class ProjectGeneratorTests: XCTestCase {
                 let target2 = nativeTargets.first { $0.name == "Other2" }
                 try expect(target2?.dependencies.count) == 2
 
-                try expect(pbxProject.targetDependencies.count) == 7
+                try expect(pbxProject.targetDependencies.count) == 8
             }
         }
     }