In 2012, the MASST program was created as a collaboration between Alissa Lange at the National Institute for Early Education Research and the New Brunswick Free Public Library (NBFPL). MASST has been implemented each summer at NBFPL since then. The content was based on effective, research-based practices from educational projects in preschool classrooms. Each session is linked to the New Jersey Department of Education Preschool Teaching and Learning Standards, and includes relevant literature and activities to promote exploration of important STEM concepts and language. The purpose of this work is to bring high-quality STEM activities to a broader audience outside of schools into the community, especially for children and families who speak Spanish.