Silverlight is supported on Mac OS X 10.4.11+ (Intel-based) on FireFox 3+ and Safari 3+. See http://www.microsoft.com/getsilverlight/Get-Started/Install/Default.aspx and click "system requirements" Remember: If Mac support is a requirement in your project, you should always ensure to test your application on that platform as well. While in most cases it will be just fine, it's still important to test it there.