The Scientist in the Classroom Partnership (SCP) is a unique, long-term program that partners STEM fellows with K-12 teachers. The SCP was adapted from the original NSF GK-12 model, with fellows and teachers working in the summer and academic year to build their partnership and design and coteach inquiry-based STEM curricula. The current study is a retrospective investigation of the first 10 years of the program to determine the impacts on university fellows and K-12 teachers and the implications for students in the participating classrooms. Results from surveys and focus groups showed that fellows gained communication, mentoring, and pedagogical skills and served as role models for students. Teachers gained STEM content knowledge, increased use of inquiry, and greater confidence in teaching science. The SCP represents an innovative model that enhances hands-on and inquiry-based teaching and learning of science through a unique partnership that brings together the university and K-12 systems.