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Thread.Start Method

Causes the operating system to change the state of the current instance to ThreadState.Running.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization = true, 
	ExternalThreading = true)]
public void Start()


The thread has already been started.


There is not enough memory available to start this thread.

Once a thread is in the ThreadState.Running state, the operating system can schedule it for execution. The thread begins executing at the first line of the method represented by the ThreadStart or ParameterizedThreadStart delegate supplied to the thread constructor. Note that the call to Start does not block the calling thread.


If this overload is used with a thread created using a ParameterizedThreadStart delegate, null is passed to the method executed by the thread.

Once the thread terminates, it cannot be restarted with another call to Start.


The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: Synchronization | ExternalThreading. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

The following example creates and starts a thread.

using System;
using System.Threading;

public class ThreadWork 
   public static void DoWork()
      for(int i = 0; i<3;i++)
         Console.WriteLine("Working thread...");
class ThreadTest
   public static void Main()
      ThreadStart myThreadDelegate = new ThreadStart(ThreadWork.DoWork);
      Thread myThread = new Thread(myThreadDelegate);
         for(int i = 0; i<3; i++)
         Console.WriteLine("In main.");

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8
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