I would go with Rails because there are several options out there to give you a good starting point for a social network. Try out Insoshi (http://portal.insosh

I would go with Rails because there are several options out there to give you a good starting point for a social network. Try out Insoshi (http://portal.insoshi.com/ http://portal.insoshi.com/) and Lovd By Less (http://lovdbyless.com/ http://lovdbyless.com/). Work with each for about a week and see if you like the way the code works and their extensibility. Also, I'd concentrate on only one factor, at this point- what platform gets you to launch the fastest? Unless you have significant ASP.net experience, Rails will probably get you there faster. Add in the massive amounts of Rails open source code that you can build off of, and I think the choice is clear. Don't pay attention to people who say "Rails can't scale" but haven't actually built a large Rails app. I run a Rails app that handles >1,000,000 hits per day, and I've spent about 3 hours resolving the scaling issues that I've run into.