This is a proposal for a workshop that will focus on empirical research related to the representation and participation of women, minorities and persons with disabilities in Science, Technology, Engineering and Mathematics (STEM) fields. The aim of the workshop is to bring together a broad array of researchers whose work informs a Science of Broadening Participation. Knowledge that is derived from a Science of Broadening Participation can further our understanding of what does and does not work to increase the scientific talent pool. A Science of Broadening Participation would employ a variety of theoretical and methodological approaches to answer research questions related to issues of access, opportunity and inclusion in STEM fields. Fundamentally, it would address important questions that deal with the inequitable distribution of educational and economic opportunities, and demonstrate the ways in which this inequity impacts the achievement of women and underrepresented minorities. The Workshop will include a small group of 25-30 distinguished scientists working in the science of broadening participation across the fields represented within the Social, Behavioral and Economic (SBE) sciences as well as a few scientists from other areas engaged in the work of broadening participation in STEM. The 2-day workshop will take place at the National Science Foundation, June 23-24, 2008.