If you already have an application written in .Net, you can scan your application with the Mono Migration Analyzer (MoMA) to determine if your application uses anything not supported by Mono.

The current release version of Mono is 2.8. (Released October 6th, 2010)

The easiest way to describe what Mono currently supports is:
Everything in .NET 4.0 except WPF, EntityFramework and WF, limited WCF.

Here is a slightly more detailed view, by .NET framework version:

Implemented Partially Implemented Not Implemented

.NET 4.0

C# 4.0
ASP.Net 4.0
ASP.Net MVC 1 and MVC 2
Managed Extensibily Framework - Shared with .NET via MS-PL license
Dynamic Language Runtime - Shared with .NET via MS-PL license
Client side OData - Shared with .NET via MS-PL license
Parallel Framework and PLINQ
CodeContracts - API complete, partial tooling
EntityFrameworks - Not available.
Server-side OData - Depends on Entity Framework.

.NET 3.5

C# 3.0
ASP.Net 3.5
LINQ to SQL - Mostly done, but a few features missing

.NET 3.0

WCF - silverlight 2.0 subset completed
WPF - no plans to implement
WF - Will implement WF 4 instead on future versions of Mono.

.NET 2.0

C# 2.0 (generics)
Core Libraries 2.0: mscorlib, System, System.Xml
ASP.Net 2.0 - except WebParts
ADO.Net 2.0
Winforms/System.Drawing 2.0 - does not support right-to-left

.NET 1.1

C# 1.0
Core Libraries 1.1: mscorlib, System, System.Xml
ASP.Net 1.1
ADO.Net 1.1
Winforms/System.Drawing 1.1
System.Management - does not map to Linux
System.EnterpriseServices - deprecated

Current Mono Trunk

This section will be updated as major components are added to Mono after the latest official release.

For details on individual classes and methods implemented by Mono, please see our class status pages ( Note that these are built from SVN versions and some methods may not be in a released version yet.