diff --git a/xunit.runner.wpf/LoadingDialog.xaml b/xunit.runner.wpf/LoadingDialog.xaml
new file mode 100644
index 0000000..6045205
--- /dev/null
+++ b/xunit.runner.wpf/LoadingDialog.xaml
@@ -0,0 +1,30 @@
+<Window x:Class="xunit.runner.wpf.LoadingDialog"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:local="clr-namespace:xunit.runner.wpf"
+        mc:Ignorable="d"
+        Title="Discovering Tests"
+        SizeToContent="WidthAndHeight"
+        ResizeMode="NoResize"
+        ShowInTaskbar="False"
+        MinHeight="100"
+        MinWidth="300"
+        WindowStartupLocation="CenterOwner">
+    <Grid>
+        <Grid.RowDefinitions>
+            <RowDefinition Height="*" />
+            <RowDefinition Height="*" />
+        </Grid.RowDefinitions>
+
+        <TextBlock Text="Discovering tests in:"
+                   HorizontalAlignment="Center"
+                   VerticalAlignment="Center"
+                   Grid.Row="0"/>
+        <TextBlock Text="{Binding Path=AssemblyFileName, RelativeSource={RelativeSource AncestorType=Window}}"
+                   HorizontalAlignment="Center"
+                   VerticalAlignment="Center"
+                   Grid.Row="1"/>
+    </Grid>
+</Window>
diff --git a/xunit.runner.wpf/LoadingDialog.xaml.cs b/xunit.runner.wpf/LoadingDialog.xaml.cs
new file mode 100644
index 0000000..f01161a
--- /dev/null
+++ b/xunit.runner.wpf/LoadingDialog.xaml.cs
@@ -0,0 +1,36 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Documents;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Shapes;
+
+namespace xunit.runner.wpf
+{
+    /// <summary>
+    /// Interaction logic for LoadingDialog.xaml
+    /// </summary>
+    public partial class LoadingDialog : Window
+    {
+        public LoadingDialog()
+        {
+            InitializeComponent();
+        }
+
+        public string AssemblyFileName
+        {
+            get { return (string)GetValue(AssemblyFileNameProperty); }
+            set { SetValue(AssemblyFileNameProperty, value); }
+        }
+
+        public static readonly DependencyProperty AssemblyFileNameProperty =
+            DependencyProperty.Register(nameof(AssemblyFileName), typeof(string), typeof(LoadingDialog));
+    }
+}
diff --git a/xunit.runner.wpf/MainWindow.xaml b/xunit.runner.wpf/MainWindow.xaml
index 50eb805..dce75e3 100644
--- a/xunit.runner.wpf/MainWindow.xaml
+++ b/xunit.runner.wpf/MainWindow.xaml
@@ -6,6 +6,8 @@
         xmlns:local="clr-namespace:xunit.runner.wpf"
         xmlns:converters="clr-namespace:xunit.runner.wpf.Converters"
         xmlns:vm="clr-namespace:xunit.runner.wpf.ViewModel"
+        xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
+        xmlns:cmd="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Platform"
         mc:Ignorable="d"
         DataContext="{Binding Main, Source={StaticResource Locator}}"
         Title="xUnit.net Test Runner"
@@ -14,6 +16,12 @@
         Height="600"
         Width="525">
 
+    <i:Interaction.Triggers>
+        <i:EventTrigger EventName="Loaded">
+            <cmd:EventToCommand Command="{Binding WindowLoadedCommand}" />
+        </i:EventTrigger>
+    </i:Interaction.Triggers>
+
     <Window.Resources>
         <converters:TestStateConverter x:Key="TestStateConverter" />
     </Window.Resources>
diff --git a/xunit.runner.wpf/MainWindow.xaml.cs b/xunit.runner.wpf/MainWindow.xaml.cs
index 2f08116..7361ef3 100644
--- a/xunit.runner.wpf/MainWindow.xaml.cs
+++ b/xunit.runner.wpf/MainWindow.xaml.cs
@@ -22,7 +22,11 @@ namespace xunit.runner.wpf
     {
         public MainWindow()
         {
+            Instance = this;
+
             InitializeComponent();
         }
+
+        public static Window Instance { get; private set; }
     }
 }
diff --git a/xunit.runner.wpf/ViewModel/MainViewModel.cs b/xunit.runner.wpf/ViewModel/MainViewModel.cs
index 817c257..a7678ba 100644
--- a/xunit.runner.wpf/ViewModel/MainViewModel.cs
+++ b/xunit.runner.wpf/ViewModel/MainViewModel.cs
@@ -22,6 +22,7 @@ namespace xunit.runner.wpf.ViewModel
 
         private bool isBusy;
         private bool isCancelRequested;
+
         public MainViewModel()
         {
             if (IsInDesignMode)
@@ -36,6 +37,7 @@ namespace xunit.runner.wpf.ViewModel
                 allTestCases, TestCaseMatches, Tuple.Create(string.Empty, TestState.All), TestComparer.Instance);
 
             this.TestCases.CollectionChanged += TestCases_CollectionChanged;
+            this.WindowLoadedCommand = new RelayCommand(OnExecuteWindowLoaded);
             this.RunCommand = new RelayCommand(OnExecuteRun, CanExecuteRun);
             this.CancelCommand = new RelayCommand(OnExecuteCancel, CanExecuteCancel);
         }
@@ -50,6 +52,7 @@ namespace xunit.runner.wpf.ViewModel
         }
 
         public ICommand ExitCommand { get; } = new RelayCommand(OnExecuteExit);
+        public ICommand WindowLoadedCommand { get; }
         public RelayCommand RunCommand { get; }
         public RelayCommand CancelCommand { get; }
 
@@ -162,7 +165,7 @@ namespace xunit.runner.wpf.ViewModel
         public ObservableCollection<TestAssemblyViewModel> Assemblies { get; } = new ObservableCollection<TestAssemblyViewModel>();
         public FilteredCollectionView<TestCaseViewModel, Tuple<string, TestState>> TestCases { get; }
 
-        private void OnExecuteOpen(object sender, ExecutedRoutedEventArgs e)
+        private async void OnExecuteOpen(object sender, ExecutedRoutedEventArgs e)
         {
             var fileDialog = new OpenFileDialog
             {
@@ -175,30 +178,48 @@ namespace xunit.runner.wpf.ViewModel
             }
 
             var fileName = fileDialog.FileName;
+            await AddAssemblies(new[] { fileName });
+        }
 
+        private async Task AddAssemblies(IEnumerable<string> fileNames)
+        {
+            var loadingDialog = new LoadingDialog { Owner = MainWindow.Instance };
             try
             {
                 using (AssemblyHelper.SubscribeResolve())
                 {
-                    using (var xunit = new XunitFrontController(
-                        useAppDomain: true,
-                        assemblyFileName: fileName,
-                        diagnosticMessageSink: new DiagnosticMessageVisitor(),
-                        shadowCopy: false)) 
-                    using (var testDiscoveryVisitor = new TestDiscoveryVisitor(xunit))
+                    loadingDialog.Show();
+                    foreach (var fileName in fileNames)
                     {
-                        xunit.Find(includeSourceInformation: false, messageSink: testDiscoveryVisitor, discoveryOptions: TestFrameworkOptions.ForDiscovery());
-                        testDiscoveryVisitor.Finished.WaitOne();
-                        allTestCases.AddRange(testDiscoveryVisitor.TestCases);
+                        loadingDialog.AssemblyFileName = fileName;
+
+                        using (var xunit = new XunitFrontController(
+                            useAppDomain: true,
+                            assemblyFileName: fileName,
+                            diagnosticMessageSink: new DiagnosticMessageVisitor(),
+                            shadowCopy: false))
+                        using (var testDiscoveryVisitor = new TestDiscoveryVisitor(xunit))
+                        {
+                            await Task.Run(() =>
+                            {
+                                xunit.Find(includeSourceInformation: false, messageSink: testDiscoveryVisitor, discoveryOptions: TestFrameworkOptions.ForDiscovery());
+                                testDiscoveryVisitor.Finished.WaitOne();
+                            });
+
+                            allTestCases.AddRange(testDiscoveryVisitor.TestCases);
+                            Assemblies.Add(new TestAssemblyViewModel(fileName));
+                        }
                     }
                 }
-
-                Assemblies.Add(new TestAssemblyViewModel(fileName));
             }
             catch (Exception ex)
             {
                 MessageBox.Show(Application.Current.MainWindow, ex.ToString());
             }
+            finally
+            {
+                loadingDialog.Close();
+            }
         }
 
         private class DiagnosticMessageVisitor : TestMessageVisitor
@@ -307,6 +328,19 @@ namespace xunit.runner.wpf.ViewModel
             Application.Current.Shutdown();
         }
 
+        private async void OnExecuteWindowLoaded()
+        {
+            try
+            {
+                IsBusy = true;
+                await AddAssemblies(Environment.GetCommandLineArgs().Skip(1));
+            }
+            finally
+            {
+                IsBusy = false;
+            }
+        }
+
         private bool CanExecuteRun()
             => !IsBusy && TestCases.Any();
 
diff --git a/xunit.runner.wpf/xunit.runner.wpf.csproj b/xunit.runner.wpf/xunit.runner.wpf.csproj
index aedb083..6655be9 100644
--- a/xunit.runner.wpf/xunit.runner.wpf.csproj
+++ b/xunit.runner.wpf/xunit.runner.wpf.csproj
@@ -89,11 +89,18 @@
     <Compile Include="Converters\TestStateConverter.cs" />
     <Compile Include="Extensions.cs" />
     <Compile Include="FilteredCollectionView.cs" />
+    <Compile Include="LoadingDialog.xaml.cs">
+      <DependentUpon>LoadingDialog.xaml</DependentUpon>
+    </Compile>
     <Compile Include="ViewModel\MainViewModel.cs" />
     <Compile Include="ViewModel\TestCaseViewModel.cs" />
     <Compile Include="ViewModel\TestAssemblyViewModel.cs" />
     <Compile Include="ViewModel\TestStateEventArgs.cs" />
     <Compile Include="ViewModel\ViewModelLocator.cs" />
+    <Page Include="LoadingDialog.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:Compile</Generator>
+    </Page>
     <Page Include="MainWindow.xaml">
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>
@@ -148,6 +155,9 @@
       <ReferenceOutputAssembly>false</ReferenceOutputAssembly>
     </ProjectReference>
   </ItemGroup>
+  <ItemGroup>
+    <WCFMetadata Include="Service References\" />
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.