Learning is an outcome in social innovation. In order to make progress on a tough issue, social innovation must interact with it, try things out., perhaps fail, and try again. And in the process, they learn more about the nature of the challenge they are trying to address, the systems that hold the problematic situation in place, and what may or may not work as a solution. Despite the widespread support for the idea for developing and using ‘lessons learned’, there is little practical guidance to do so. This resource provides one way to go about it.