Children and youth have benefited from afterschool programs in terms of academic, physical health, school attendance, promotion, graduation, and social and emotional outcomes. Afterschool programming in general—and science, technology, engineering, and math (STEM) afterschool programming in particular—is also popular among school officials and parents. To obtain a national picture of why and how principals and district leaders partner with external organizations as STEM afterschool providers, the authors administered a survey to a nationally representative sample of public school principals (kindergarten through grade 8) in November and December 2022. Schools have direct access to youth and families and, therefore, have great potential to influence afterschool choices. The authors surveyed and interviewed school and district leaders to understand their STEM afterschool needs and interests, including the details on how these leaders go about partnering with STEM afterschool providers. The surveys and interviews illuminated how administrators learn about potential afterschool partners, what they look for in a partnership, and why they renew them. (author abstract)