Using Yosso’s community cultural wealth as a theoretical lens, we sought to understand how science, technology, engineering, and mathematics (STEM) summer programs cultivated the interest and participation of Black women and girls in these disciplines. The study drew primarily from the interviews of 14 Black women and girls from two case studies investigating the experiences of students of color in summer STEM programs. Findings revealed the programs were influential in enhancing participants’ existing aspirational, social, and familial capital garnered through inter- and intrapersonal attributes. We also advance the term program families to describe a distinctive fictive kinship fostered through participation in these programs.