Despite detailed analyses by researchers from a variety of disciplines, the number of women and underrepresented ethnic minorities entering and completing programs in science, technology, engineering, and mathematics (STEM) is increasing more slowly than had been hoped. The articles contained in this issue represent cutting-edge research by some of the top researchers in social psychology, developmental psychology, education, and medical sciences. The articles cover broad ground with regard to topic of study, age focus, methodology, and level of analysis. The research contained in the issue has the potential to have an impact on policy and program development and serves as a catalyst for further thinking on this important social issue.