diff --git a/critterfolio/CritterFolio/CritterFolioTests/UnitTest1.cs b/critterfolio/CritterFolio/CritterFolioTests/UnitTest1.cs
index f87af3e..689b72e 100644
--- a/critterfolio/CritterFolio/CritterFolioTests/UnitTest1.cs
+++ b/critterfolio/CritterFolio/CritterFolioTests/UnitTest1.cs
@@ -16,12 +16,12 @@ public class Tests
     [Test]
     public async Task TestAddingCritter()
     {
-        Assert.That(await DatabaseService.AddCritter(new Critter(){Name = "Test Critter"}), Is.True);
+        Assert.That(await DatabaseService.AddCritter(new Critter{Name = "Test Critter"}), Is.True);
     }
 
     [Test]
-    public async Task TestGettingCritter()
+    public async Task TestGettingCritterThatDoesntExist()
     {
-        Assert.That(await DatabaseService.GetCritter(-1), Is.True); 
+        Assert.That(await DatabaseService.GetCritter(-1), Is.False);
     }
 }
\ No newline at end of file
diff --git a/critterfolio/class-diagram.puml b/critterfolio/class-diagram.puml
new file mode 100644
index 0000000..e4fac0d
--- /dev/null
+++ b/critterfolio/class-diagram.puml
@@ -0,0 +1,74 @@
+@startuml
+!theme crt-green
+skinparam classAttributeIconSize 0
+skinparam monochrome true
+skinparam shadowing false
+
+package "CritterFolio.DataModels" {
+
+    enum Gender {
+        Male
+        Female
+    }
+
+    class Critter {
+        + Id : int
+        + ProfileImagePath : string
+        + Name : string
+        + Gender : Gender
+        + DateOfBirth : DateTime
+        + FatherId : int
+        + MotherId : int
+        + Notes : string
+    }
+
+    class CritterEvent {
+        + Id : int
+        + CritterId : int
+        + Name : string
+        + DateTime : DateTime
+        + Description : string
+    }
+
+    class Document {
+        + Id : int
+        + CritterId : int
+        + Name : string
+        + Path : string
+        + Description : string
+    }
+}
+
+package "CritterFolio.Services" {
+    class DatabaseService <<static>> {
+        - {static} _db : SQLiteAsyncConnection
+        + {static} Init() : Task
+        + {static} ClearAllTables() : Task
+        .. Critter Operations ..
+        + {static} AddCritter(critter : Critter) : Task<bool>
+        + {static} UpdateCritter(critter : Critter) : Task<bool>
+        + {static} DeleteCritter(critter : Critter) : Task<bool>
+        + {static} GetAllCritters() : Task<List<Critter>>
+        + {static} GetCritter(id : int) : Task<Critter>
+        .. Document Operations ..
+        + {static} AddDocument(doc : Document) : Task<bool>
+        + {static} GetAllDocumentsForCritter(id : int) : Task<List<Document>>
+        .. Event Operations ..
+        + {static} AddEvent(ev : CritterEvent) : Task<bool>
+        + {static} GetAllEventsForCritter(id : int) : Task<List<CritterEvent>>
+    }
+}
+
+' Relationships
+Critter "1" *-- "0..*" CritterEvent : has >
+Critter "1" *-- "0..*" Document : has >
+Critter --> Gender : uses
+
+' Self-references for lineage
+Critter --> Critter : FatherId / MotherId
+
+' Service usage
+DatabaseService ..> Critter : manages
+DatabaseService ..> CritterEvent : manages
+DatabaseService ..> Document : manages
+@enduml