diff --git a/SolutionParityChecker.App/SolutionParityChecker.App.csproj b/SolutionParityChecker.App/SolutionParityChecker.App.csproj
index 081513a..54cc2ec 100644
--- a/SolutionParityChecker.App/SolutionParityChecker.App.csproj
+++ b/SolutionParityChecker.App/SolutionParityChecker.App.csproj
@@ -26,4 +26,8 @@
         <PackageReference Condition="'$(Configuration)' == 'Debug'" Include="Avalonia.Diagnostics" Version="11.0.0-preview8"/>
         <PackageReference Include="CommunityToolkit.Mvvm" Version="8.2.0"/>
     </ItemGroup>
+
+    <ItemGroup>
+      <ProjectReference Include="..\SolutionParityChecker\SolutionParityChecker.csproj" />
+    </ItemGroup>
 </Project>
diff --git a/SolutionParityChecker.App/ViewModels/MainWindowViewModel.cs b/SolutionParityChecker.App/ViewModels/MainWindowViewModel.cs
index dac9045..c56147a 100644
--- a/SolutionParityChecker.App/ViewModels/MainWindowViewModel.cs
+++ b/SolutionParityChecker.App/ViewModels/MainWindowViewModel.cs
@@ -1,4 +1,6 @@
 using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.IO;
 using System.Text;
 using System.Threading;
@@ -13,14 +15,37 @@ namespace SolutionParityChecker.App.ViewModels;
 
 public partial class MainWindowViewModel : ViewModelBase
 {
-    public string SolutionFolderPath { get; set; } = string.Empty;
-    public string SolutionFilePath { get; set; } = string.Empty;
+    [ObservableProperty]
+    private string _solutionFolderPath;
+
+    [ObservableProperty]
+    private string _solutionFilePath;
 
     [ObservableProperty]
     private string? _fileText;
 
+    [ObservableProperty]
+    private ObservableCollection<string> _parityResults = new ObservableCollection<string>()
+    {
+        "Test"
+    };
+
     [RelayCommand]
-    private async Task OpenFile(CancellationToken token)
+    private async Task ExecuteParityChecker(CancellationToken token)
+    {
+        var results = SolutionParityChecker.CompareSolutionAndCSharpProjects(
+            SolutionFolderPath,
+            SolutionFilePath
+        );
+        ParityResults.Clear();
+        foreach (var result in results)
+        {
+            ParityResults.Add(result);
+        }
+    }
+
+    [RelayCommand]
+    private async Task LoadSolutionFile(CancellationToken token)
     {
         ErrorMessages?.Clear();
         try
@@ -29,17 +54,7 @@ public partial class MainWindowViewModel : ViewModelBase
             if (file is null)
                 return;
 
-            // Limit the text file to 1MB so that the demo won't lag.
-            if ((await file.GetBasicPropertiesAsync()).Size <= 1024 * 1024 * 1)
-            {
-                await using var readStream = await file.OpenReadAsync();
-                using var reader = new StreamReader(readStream);
-                FileText = await reader.ReadToEndAsync(token);
-            }
-            else
-            {
-                throw new Exception("File exceeded 1MB limit.");
-            }
+            SolutionFilePath = file.Path.AbsolutePath;
         }
         catch (Exception e)
         {
@@ -48,26 +63,16 @@ public partial class MainWindowViewModel : ViewModelBase
     }
 
     [RelayCommand]
-    private async Task SaveFile()
+    private async Task LoadSolutionFolder(CancellationToken token)
     {
         ErrorMessages?.Clear();
         try
         {
-            var file = await DoSaveFilePickerAsync();
-            if (file is null)
+            var folder = await DoOpenFolderPickerAsync();
+            if (folder is null)
                 return;
 
-            // Limit the text file to 1MB so that the demo won't lag.
-            if (FileText?.Length <= 1024 * 1024 * 1)
-            {
-                var stream = new MemoryStream(Encoding.Default.GetBytes((string)FileText));
-                await using var writeStream = await file.OpenWriteAsync();
-                await stream.CopyToAsync(writeStream);
-            }
-            else
-            {
-                throw new Exception("File exceeded 1MB limit.");
-            }
+            SolutionFolderPath = folder.Path.AbsolutePath;
         }
         catch (Exception e)
         {
@@ -98,7 +103,7 @@ public partial class MainWindowViewModel : ViewModelBase
         return files?.Count >= 1 ? files[0] : null;
     }
 
-    private async Task<IStorageFile?> DoSaveFilePickerAsync()
+    private async Task<IStorageFolder?> DoOpenFolderPickerAsync()
     {
         // For learning purposes, we opted to directly get the reference
         // for StorageProvider APIs here inside the ViewModel.
@@ -106,7 +111,7 @@ public partial class MainWindowViewModel : ViewModelBase
         // For your real-world apps, you should follow the MVVM principles
         // by making service classes and locating them with DI/IoC.
 
-        // See DepInject project for a sample of how to accomplish this.
+        // See IoCFileOps project for an example of how to accomplish this.
         if (
             Application.Current?.ApplicationLifetime
                 is not IClassicDesktopStyleApplicationLifetime desktop
@@ -114,8 +119,10 @@ public partial class MainWindowViewModel : ViewModelBase
         )
             throw new NullReferenceException("Missing StorageProvider instance.");
 
-        return await provider.SaveFilePickerAsync(
-            new FilePickerSaveOptions() { Title = "Save Text File" }
+        var folder = await provider.OpenFolderPickerAsync(
+            new FolderPickerOpenOptions() { Title = "Open Text File", AllowMultiple = false }
         );
+
+        return folder?.Count >= 1 ? folder[0] : null;
     }
 }
diff --git a/SolutionParityChecker.App/ViewModels/ViewModelBase.cs b/SolutionParityChecker.App/ViewModels/ViewModelBase.cs
index ebf744e..f85eddd 100644
--- a/SolutionParityChecker.App/ViewModels/ViewModelBase.cs
+++ b/SolutionParityChecker.App/ViewModels/ViewModelBase.cs
@@ -9,7 +9,7 @@ public partial class ViewModelBase : ObservableObject
     {
         ErrorMessages = new ObservableCollection<string>();
     }
-    
-    [ObservableProperty] 
+
+    [ObservableProperty]
     private ObservableCollection<string>? _errorMessages;
-}
\ No newline at end of file
+}
diff --git a/SolutionParityChecker.App/Views/MainWindow.axaml b/SolutionParityChecker.App/Views/MainWindow.axaml
index 639da74..aac9435 100644
--- a/SolutionParityChecker.App/Views/MainWindow.axaml
+++ b/SolutionParityChecker.App/Views/MainWindow.axaml
@@ -11,18 +11,18 @@
     <Design.DataContext>
         <!-- This only sets the DataContext for the previewer in an IDE,
              to set the actual DataContext for runtime, set the DataContext property in code (look at App.axaml.cs) -->
-        <viewModels:MainWindowViewModel/>
+        <viewModels:MainWindowViewModel />
     </Design.DataContext>
     <Panel>
         <StackPanel>
             <TextBlock>Welcome to Avalonia!</TextBlock>
-            <Button Click="LoadSolutionFolder">Select Solution Folder</Button>
-            <Button Click="LoadSolutionFile">Select Solution File</Button>
-            <Button Command="{Binding OpenFileCommand}">Open File</Button>
-            <Button Command="{Binding SaveFileCommand}">Save File</Button>
+            <Button Command="{Binding LoadSolutionFolderCommand}" >Select Solution Folder</Button>
+            <Button Command="{Binding LoadSolutionFileCommand}">Select Solution File</Button>
+            <Button Command="{Binding ExecuteParityCheckerCommand}">Check Solution Parity</Button>
             <TextBlock Name="SolutionFilePath" Text="{Binding SolutionFilePath}" />
             <TextBlock Name="SolutionFolderPath" Text="{Binding SolutionFolderPath}" />
-            <ListBox DockPanel.Dock="Bottom" ItemsSource="{Binding ErrorMessages}"/>
+            <ListBox Name="Results" ItemsSource="{Binding ParityResults}"/>
+            <ListBox ItemsSource="{Binding ErrorMessages}"/>
         </StackPanel>
     </Panel>
     
diff --git a/SolutionParityChecker.App/Views/MainWindow.axaml.cs b/SolutionParityChecker.App/Views/MainWindow.axaml.cs
index 53ebbc5..ca21c9d 100644
--- a/SolutionParityChecker.App/Views/MainWindow.axaml.cs
+++ b/SolutionParityChecker.App/Views/MainWindow.axaml.cs
@@ -1,5 +1,6 @@
 using Avalonia.Controls;
 using Avalonia.Interactivity;
+using SolutionParityChecker.App.ViewModels;
 
 namespace SolutionParityChecker.App.Views;
 
@@ -9,14 +10,4 @@ public partial class MainWindow : Window
     {
         InitializeComponent();
     }
-
-    private void LoadSolutionFolder(object? sender, RoutedEventArgs e)
-    {
-        SolutionFolderPath.Text = "Solution folder path";
-    }
-
-    private void LoadSolutionFile(object? sender, RoutedEventArgs e)
-    {
-        SolutionFilePath.Text = "Solution file path";
-    }
 }
diff --git a/SolutionParityChecker/SolutionParityChecker.cs b/SolutionParityChecker/SolutionParityChecker.cs
index 2812b75..5f5e338 100644
--- a/SolutionParityChecker/SolutionParityChecker.cs
+++ b/SolutionParityChecker/SolutionParityChecker.cs
@@ -4,13 +4,26 @@ namespace SolutionParityChecker;
 
 public static class SolutionParityChecker
 {
-    public static void CompareSolutionAndCSharpProjects(
+    public static List<string> CompareSolutionAndCSharpProjects(
         string solutionFolderPath,
         string solutionFilePath
-    ) { }
+    )
+    {
+        var csprojList = RetrieveAllCSharpProjectNamesFromFolder(solutionFolderPath);
+        var solutionFile = ParseSolutionFileFromPath(solutionFilePath);
+        ArgumentNullException.ThrowIfNull(solutionFile);
+        var projectsMissingFromSolution = FindProjectsMissingFromSolution(csprojList, solutionFile);
+
+        return projectsMissingFromSolution;
+    }
 
     public static string[] RetrieveAllCSharpProjectNamesFromFolder(string solutionFolderPath)
     {
+        // if solutionFolderPath does not end with a slash, add one
+        if (solutionFolderPath[^1] != Path.DirectorySeparatorChar)
+        {
+            solutionFolderPath += Path.DirectorySeparatorChar;
+        }
         var csprojList = Directory.GetFiles(
             solutionFolderPath,
             "*.csproj",