In recent decades, efforts to diversify Science, Technology, Engineering, and Mathematics (STEM) fields have relied on a variety of recruitment and retention programs designed to improve access and outcomes of traditionally underrepresented populations. Examining how such programs emerge within institutions of higher education in the United States -- including original motivations, sources of funding, and institutional agents involved in the development and stages of implementation of the program -- reveals a lack of strategic and systematic approach to diversifying these fields. Drawing on interviews with administrators representing nearly 40 STEM intervention programs at 10 universities in the United States, this study examines program origins through the lens of institutional isomorphism. The analyses provide evidence of mimetic and coercive isomorphism, and little evidence of strategic decision-making and resource allocation.