diff --git a/tdd-todo-list.CSharp.Main/ToDoList.cs b/tdd-todo-list.CSharp.Main/ToDoList.cs
index 835cb600..a236a7fc 100644
--- a/tdd-todo-list.CSharp.Main/ToDoList.cs
+++ b/tdd-todo-list.CSharp.Main/ToDoList.cs
@@ -8,5 +8,110 @@ namespace tdd_todo_list.CSharp.Main
 {
     public class TodoList
     {
+        public List<string> _list;
+        public List<bool> _status;
+
+        public TodoList()
+        {
+            _list = new List<string>();
+            _status = new List<bool>();
+        }
+
+        public bool AddTask(string task)
+        {
+            _list.Add(task);
+            _status.Add(false);
+            return true;
+        }
+
+        public bool ShowAllTasks()
+        {
+            for (int i = 0; i < _list.Count; i++)
+            {
+                Console.WriteLine($"Task: {_list[i]}, Status: {_status[i]}");
+            }
+            return true;
+        }
+
+        public bool UpdateStatus(string task)
+        {
+            int inx = _list.IndexOf(task);
+
+            if (inx == -1) { return false; }
+
+            _status[inx] = true;
+            return true;
+        }
+
+        public bool ShowCompleteTasks()
+        {
+            for (int i = 0; i < _list.Count; i++)
+            {
+                if (_status[i])
+                {
+                    Console.WriteLine($"Task: {_list[i]}, Status: {_status[i]}");
+                }
+            }
+            return true;
+        }
+
+        public bool ShowInCompleteTasks()
+        {
+            for (int i = 0; i < _list.Count; i++)
+            {
+                if (!_status[i])
+                {
+                    Console.WriteLine($"Task: {_list[i]}, Status: {_status[i]}");
+                }
+            }
+            return true;
+        }
+
+        public string SearchTask(string task)
+        {
+            string result = "Task Not Found";
+
+            int inx = _list.IndexOf(task);
+
+            if (inx == -1) { return result; }
+
+            result = $"The task, {task}, has been found at index {inx}";
+            return result;
+        }
+
+
+        public bool RemoveTask(string task)
+        {
+            int inx = _list.IndexOf(task);
+
+            if (inx == -1) { return false; }
+
+            _list.RemoveAt(inx);
+            _status.RemoveAt(inx);
+            return true;
+        }
+
+        public bool ShowAllTasksAlphabeticallyAcending()
+        {
+            List<string> alphabeticalList = new List<string>(_list);
+            alphabeticalList.Sort(StringComparer.OrdinalIgnoreCase);
+            for (int i = 0; i < _list.Count; i++)
+            {
+                Console.WriteLine($"Task: {alphabeticalList[i]}");
+            }
+            return true;
+        }
+
+        public bool ShowAllTasksAlphabeticallyDecending()
+        {
+            List<string> alphabeticalList = new List<string>(_list);
+            alphabeticalList.Sort(StringComparer.OrdinalIgnoreCase);
+            alphabeticalList.Reverse();
+            for (int i = 0; i < _list.Count; i++)
+            {
+                Console.WriteLine($"Task: {alphabeticalList[i]}");
+            }
+            return true;
+        }
     }
 }
diff --git a/tdd-todo-list.CSharp.Test/CoreTests.cs b/tdd-todo-list.CSharp.Test/CoreTests.cs
index 084cce19..2ed6f7ab 100644
--- a/tdd-todo-list.CSharp.Test/CoreTests.cs
+++ b/tdd-todo-list.CSharp.Test/CoreTests.cs
@@ -6,12 +6,100 @@ namespace tdd_todo_list.CSharp.Test
     [TestFixture]
     public class CoreTests
     {
+        [Test]
+        public void TestAdd()
+        {
+            TodoList core = new TodoList();
+            Assert.That(core._list.Count, Is.EqualTo(0));
+            core.AddTask("Clean");
+            Assert.That(core._list.Count, Is.EqualTo(1));
+            core.AddTask("Tidy");
+            Assert.That(core._list.Count, Is.EqualTo(2));
+        }
+
+        [Test]
+        public void TestShowAll()
+        {
+            TodoList core = new TodoList();
+            core.AddTask("Clean");
+            core.AddTask("Tidy");
+            Assert.That(core.ShowAllTasks, Is.True);
+        }
+
+
+        [Test]
+        public void TestUpdate()
+        {
+            TodoList core = new TodoList();
+            core.AddTask("Clean");
+            core.AddTask("Tidy");
+            Assert.That(core._status[0], Is.False);
+            Assert.That(core._status[1], Is.False);
+            core.UpdateStatus("Clean");
+            Assert.That(core._status[0], Is.True);
+            Assert.That(core._status[1], Is.False);
+        }
+
+        [Test]
+        public void TestUpdateOfTaskNotOnList()
+        {
+            TodoList core = new TodoList();
+            core.AddTask("Clean");
+            Assert.That(core._status[0], Is.False);
+            core.UpdateStatus("clean");
+            Assert.That(core._status[0], Is.False);
+            Assert.That(core.UpdateStatus("shop"), Is.False);
+        }
 
         [Test]
-        public void FirstTest()
+        public void TestShowOnly()
         {
             TodoList core = new TodoList();
-            Assert.Pass();
+            core.AddTask("Clean");
+            core.AddTask("Tidy");
+            core.UpdateStatus("Clean");
+            Assert.That(core.ShowCompleteTasks(), Is.True);
+            Assert.That(core.ShowInCompleteTasks(), Is.True);
         }
+
+        [Test]
+        public void TestSearch()
+        {
+            TodoList core = new TodoList();
+            core.AddTask("Clean");
+            core.AddTask("Tidy");
+            Assert.That(core.SearchTask("Clean"), Is.EqualTo("The task, Clean, has been found at index 0"));
+            Assert.That(core.SearchTask("clean"), Is.EqualTo("Task Not Found"));
+        }
+
+
+        [Test]
+        public void TestRemove()
+        {
+            TodoList core = new TodoList();
+            Assert.That(core._list.Count, Is.EqualTo(0));
+            core.AddTask("Clean");
+            Assert.That(core._list.Count, Is.EqualTo(1));
+            core.AddTask("Tidy");
+            Assert.That(core._list.Count, Is.EqualTo(2));
+
+            Assert.That(core.RemoveTask("tidyclean"), Is.False);
+
+            core.RemoveTask("Clean");
+            Assert.That(core._list.Count, Is.EqualTo(1));
+            core.RemoveTask("Tidy");
+            Assert.That(core._list.Count, Is.EqualTo(0));
+        }
+
+        [Test]
+        public void TestSorting()
+        {
+            TodoList core = new TodoList();
+            core.AddTask("Clean");
+            core.AddTask("Tidy");
+            Assert.That(core.ShowAllTasksAlphabeticallyAcending(), Is.True);
+            Assert.That(core.ShowAllTasksAlphabeticallyDecending(), Is.True);
+        }
+
     }
 }
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