Students are more likely to learn in college science, technology, engineering, and math (STEM) classrooms when instructors use teacher discourse moves (TDMs) that encourage student engagement and learning. However, although teaching practices are well studied, TDMs are not well understood in college STEM classrooms. In STEM courses at a minority-serving institution (MSI; n = 74), we used two classroom observation protocols to investigate teaching practices and TDMs across disciplines, instructor types, years of teaching experience, and class size. We found that instructors guide students in active learning activities, but they use authoritative discourse approaches. In addition, chemistry instructors presented more than biology instructors. Also, teaching faculty had relatively high dialogic, interactive discourse, and neither years of faculty teaching experience nor class size had an impact on teaching practices or TDMs. Our results have implications for targeted teaching professional development efforts across instructor and course characteristics to improve STEM education at MSIs.