This documentation is archived and is not being maintained.

ThreadStart Delegate

Represents the method that executes on a Thread.

Namespace:  System.Threading
Assembly:  mscorlib (in mscorlib.dll)

public delegate void ThreadStart()

When a managed thread is created, the method that executes on the thread is represented by a ThreadStart delegate or a ParameterizedThreadStart delegate that is passed to the Thread constructor. The thread does not begin executing until the Thread.Start method is called. Execution begins at the first line of the method represented by the ThreadStart or ParameterizedThreadStart delegate.


Visual Basic and C# users can omit the ThreadStart or ParameterizedThreadStart delegate constructor when creating a thread. In Visual Basic, use the AddressOf operator when passing your method to the Thread constructor; for example, Dim t As New Thread(AddressOf ThreadProc). In C#, simply specify the name of the thread procedure. The compiler selects the correct delegate constructor.


In version 2.0 of the .NET Framework, creating a ThreadStart delegate for a static method in C++ requires only one parameter: the address of the callback method, qualified by the class name. In earlier versions two parameters were required when creating a delegate for a static method: zero (null) and the method address. For an instance method, all versions require two parameters: the instance variable and the method address.

The following code example shows the syntax for creating and using a ThreadStart delegate with an instance method and with a static method.

For another simple example that demonstrates how to create a ThreadStart delegate, see the Thread.Start() method overload. For more information about thread creation, see Creating Threads and Passing Data at Start Time.

using System;
using System.Threading;

class Test
    static void Main() 
        // To start a thread using a static thread procedure, use the 
        // class name and method name when you create the ThreadStart 
        // delegate. Beginning in version 2.0 of the .NET Framework, 
        // it is not necessary to create a delegate explicitly.  
        // Specify the name of the method in the Thread constructor,  
        // and the compiler selects the correct delegate. For example: 
        // Thread newThread = new Thread(Work.DoWork); 
        ThreadStart threadDelegate = new ThreadStart(Work.DoWork);
        Thread newThread = new Thread(threadDelegate);

        // To start a thread using an instance method for the thread  
        // procedure, use the instance variable and method name when  
        // you create the ThreadStart delegate. Beginning in version 
        // 2.0 of the .NET Framework, the explicit delegate is not 
        // required. 
        Work w = new Work();
        w.Data = 42;
        threadDelegate = new ThreadStart(w.DoMoreWork);
        newThread = new Thread(threadDelegate);

class Work 
    public static void DoWork() 
        Console.WriteLine("Static thread procedure."); 
    public int Data;
    public void DoMoreWork() 
        Console.WriteLine("Instance thread procedure. Data={0}", Data); 

/* This code example produces the following output (the order 
   of the lines might vary):
Static thread procedure.
Instance thread procedure. Data=42

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0