This study reports the findings of a two-year intensive professional development (PD) program situated in the northeastern United States for secondary mathematics and science teachers to support them in transforming their STEM instruction to incorporate SocioScientific Issues (SSI). This PD focused on developing units of study that integrated student-centered, authentic learning experiences grounded in social justice issues. Findings indicate that after participation in the USTRIVE project, teachers displayed growth in their ability to incorporate components of the instructional framework for SSI introduced in the PD into their teaching. This is consistent with previous research that SSI-focused PD can increase teachers’ knowledge of, and teaching practices toward SSI, resulting in more meaningful STEM learning experiences for students. As such, the USTRIVE PD model and framework may provide a useful guide for other SSI and social justice PD programs. Connections of these findings to student engagement, teachers learning, and challenges encountered in SSI implementation are explored.