This GovLab Working Paper is an attempt to describe the promise and challenge of evaluating new practices of problem solving in governance, specifically citizen-engagement interventions. The purpose is to inform those innovators who are eager to develop a deeper insight into what works for the key steps, opportunities and challenges involved when assessing impact. In addition, the paper aims to develop a foundation for further interdisciplinary research and debate. This paper summarizes the recent lessons learned in the field of evaluation and examines how new methods could help assess the impacts of participatory governance and emerging social technologies used in governance. This work is not meant to be a comprehensive review of current approaches to evaluating new governance initiatives but is intended to frame the issues involved, and suggest where work needs to be done to develop better assessments. We are also providing an annotated and open bibliography for further reading, inviting others to expand upon it.