Action research is one strategic approach teachers can use to positively influence teaching and learning in their classrooms, their schools, and beyond. Action research encourages best practice instruction, supports student learning, inspires school-university partnerships, advances the four professional development school (PDS) core purposes, and cultivates teacher leaders. This article illustrates the impact of teacher leadership on student learning in the STEM areas by reporting summaries of three teacher-led action research projects conducted in partnership with one university's Center for STEM Education. The article concludes that action research is a worthwhile endeavor for both teachers and students. [ABSTRACT FROM AUTHOR]