How to pick an open source project to join?

I am interested to join an Open Source project using .net; I would like to be able to choose between a mature project and a starting one, as well as other criteria. What do you suggest? (specific projects are welcomed).

Later edit:

I am disappointed by the arrogant comments / answers received so far. Picking an OS project to contribute to is not a simple task. I have spent many hours today doing this. My experience shows that:

• few projects advertise how to contribute to them
• few projects even let you contribute
• a lot of projects expect you to contribute by writing docs and answering user questions
• there are many projects that are "dead"
• no everybody uses OS software written in .net - it is a starting community - so the criteria "contribute to the project you use" is not useful

I believe this question is far from being answered. I have carefully read the related questions, there are some good points there, yet nothing truly revealing.

From stackoverflow

• The obvious criteria would be to pick a project in an area that interests you.

• Irrespective of Bogdan's comment, @Rob's suggestion is a good one for a couple of reasons.

  If you pick an open source project that is in an area that interests you, e.g. if you're into music then working on the Audacity project, then:

  1. you will be more motivated because the project is trying to solve aspects of a problem space that you have an interest in
  2. you bring your particular knowledge to the project which will be useful to the project
  3. you will (probably) learn more about your area of interest from others involved in the project
  4. you finish up with an improved version of the project to use

  HTH

  cheers

• Here's what I would do:

  • Find a project of interest to you. Maybe you want to learn about some specific technology / application or maybe you just want to experience how open source projects differ from corporate projects.
  • Look at the code, documentation, forum and so forth and think about if their style / conventions is suitable for you.
  • Present yourself to the project members and let them know what you can bring to the party.
  • Write code and enjoy.

• Join the team of software that you actually use or need. As a user, you will have more incentive to get it done and insight about how the software should work.

  Bogdan Gavril : I don't use OS software written in .net, apart from NHibernate, which I consider to be out of my league at this point.

• I think the most important criteria for me would be

  1. A project in a language I'm comfortable in or eager to learn
  2. A project which has active members. Who wants to join an open source project and do it all yourself
  3. A project that I would use at home.
  JaredPar : Love it. Done voted for a subjective question answer.

• I have found a very interesting .net project - it is called Terranium.

  http://www.codeplex.com/terrarium2/

  It is a game where you programatically create an animal and interact with other animals. It would be fun to also contribute to this project, but I have yet to see if they (it is run by a MS MVP) accept this.

  leppie : Very old and outdated, but I heard it was being revived. Best would be to go for a project with an active community (you feel quicker at home, and help is at hand faster).

  Bogdan Gavril : Thanks! You're right, it is old and left alone...

• I find my own interests reflected in your question, so here are some o-s projects that I am considering:

  • SharpDevelop - they've gone a long way, and still a long way to go :-). I think some improvements for code navigation and code refactoring a la ReSharper (or even Eclipse) would be very cool.
  • NHibernate - support for generics (although I think Ayende already has this covered); support tools - visual editors for xml configs, maybe a visual tool (VS addin?) that takes one of {model, mappings, database_schema } and generates the other two.

• Check out Banshee from Aaron Bockover. It's written in C# for Mono, and is also part of the GnomeLove initiative, so there are bugs tagged specifically for new contributors.

  When I have the free time to hack on something myself, this will be my first choice. It's a really good music player.

• Join IronScheme! :)

  Update:

  Best would be to go for a project with an active community (you feel quicker at home, and help is at hand faster).