As the field of PER grows and diversifies, it is increasingly difficult for newcomers to gain an appreciation of the major findings across all sub-domains, to discern global themes, and to recognize gaps in the literature. We believe that a synthesis of the research could play an important role for both researchers and practitioners. Our goal is to produce a resource that addresses the following central questions:
* What has PER contributed to our current knowledge of teaching and learning of physics?
* What would we be lacking today without decades of continued PER?
* How has PER evolved over the decades (in terms of research questions tackled, instruments employed, methodologies used, etc.)? What were the major turning points in PER history?
* How has physics teaching and learning changed (improved) over the decades due to the direct impact of PER?
* How has PER benefited from other disciplines (e.g. cognitive psychology, educational psychology, pedagogical research, instructional design research, etc.) and vice versa?

We propose to invite a broad spectrum of researchers with international reputations to contribute chapters that synthesize results on important topics.