Getting more young people engaged in STEM is essential in part because jobs in STEM continue to grow at rates double those of non-STEM professions. Providing greater opportunities for STEM learning isn't just about preparing the future workforce. As the world continues to rely more and more on technology, everyone will require a greater level of STEM literacy and fluency to understand how science and technology play a role. Greater STEM literacy also helps prepare students to better understand challenges and issues that affect them and their communities. Research shows that what happens outside of school can be equally as important as what happens inside of school in terms of activating students' interest in STEM or other school subjects. The 2020 America After 3PM report on afterschool demand and supply in the United States, "Demand Grows, Opportunity Shrinks," found a dramatic escalation in the unmet demand for afterschool programs since the last survey in 2014. This report offers a deeper dive into the 2020 America After 3PM survey findings to provide important new insights about STEM learning in afterschool, a first-ever look at trends in afterschool STEM learning, areas for further exploration, and recommendations to help ensure that all young people have access to high-quality afterschool STEM opportunities. [For the report, "America after 3PM: Demand Grows, Opportunity Shrinks," see ED611372. For the executive summary of this report, see ED617409.]