When setting out on a new project, you risk painting yourself into a corner if you take ill-conceived decisions without knowing the choices you have. The book Application Architecture Guide 2.0 provides design-level guidance for the architecture and design of applications built on the .NET Framework. It is a collaborative effort between Patterns & Practices, Product teams, and industry experts. The guide in PDF format (2.64MB) is freely downloadable from CodePlex.I have benefitted a lot from reading the Patterns & Practices guide "Improving .NET Application Performance and Scalability" that was published years ago and look forward to reading this new guide from P&P. There aren't many comprehensive guides like these for .NET practitioners and this guide thankfully fills a void. It's also a nice idea that they are seeking feedback from the community.