Many national reports call for K-12 teachers to increase their content knowledge, expertise in student-centered learning methods, and skills in working with an increasingly diverse student population. Historically, most teacher professional development (PD) has not addressed these multiple challenges. We evaluated two PD models--research experiences for teachers and online PD--for their comparative impacts on middle and high school teachers' understanding of, preparedness to use, and actual use of proven STEM teaching methods and STEM career information. The programs were unique in their focus on equipping teachers with a pedagogical "tool kit" that supports ongoing changes in teaching and assessment methods, STEM content, use of technology, and working with diverse students. Findings indicate that both program models increased teachers' preparedness to use and their frequency of use of the targeted STEM teaching methods. Teachers who had summer research experiences gained additional benefits.