The National Research Council, through its Board on Science Education, will carry out a synthesis study of informal science learning based on a workshop funded by a prior NSF planning grant. The intellectual merit of this project is based on the formation of a committee of experts representative of the diversity of the field who will engage in a fact-finding process on learning science in informal settings, deliberate about the evidence and produce a major report that will be published by the National Academies Press. The study will describe the status of knowledge in the field currently, articulate a common framework for the next generation of research on informal science learning and provide guidance to the community of practice. By presenting what we know about the characteristics of effective informal science learning environments across a range of outcome measures, the study will achieve broader impacts by assisting practitioners, policymakers and researchers in directing their efforts towards realizing the potential of informal science education for advancing public science literacy.