A collaborative of STEM (science, technology, engineering, and mathematics) and education faculty developed a STEM certificate aimed at elementary education majors. A four-phase process model was used to create and evaluate courses. The certificate is comprised of three interdisciplinary, team-taught, lab-based courses: Environmental Biology, Chemistry of Life, and Engineering in Your World. The biology and chemistry courses are inquiry based, whereas the engineering course is project based. Each of the courses is cotaught by a faculty member in STEM and a faculty member in education. The goal of the certificate is to improve elementary education majors' STEM competence and confidence. Initial assessment results showed significant gains in confidence and competence on the basis of knowledge test items. Curriculum continues to be refined on the basis of assessments and changing state and national education standards. (Contains 3 tables and 1 figure.)