ayi <t>This article offers a fairly comprehensive explanation:<br/> <br/> "Comparing the Timer Classes in the .NET Framework Class Library" - also available as a .chm file<br/> <br/> The specific difference appears to be that System.Timers.Timer is geared towards multithreaded applications and is therefore thread-safe via its SynchronizationObject property, whereas System.Threading.Timer is ironically not thread-safe out-of-the-box.<br/> <br/> I don't believe that there is a difference between the two as it pertains to how small your intervals can be.</t>