Many institutions are preparing graduate students and postdoctorals (future faculty) for effective teaching in undergraduate science, technology, engineering, and mathematics (STEM). Interestingly, little is known about beneficial features of teaching-development (TD) programs for future faculty after they transition into professoriate roles, and how these features are useful. We investigated the features of a TD program for STEM future faculty that were influential to their current teaching as faculty members, and in transitioning into faculty positions. Data were collected using in-depth interviews with 10 alumni (current faculty) from different STEM disciplines one to five years after participating in the TD program. Three themes emerged from this study: (1) exposure to multiple effective teaching approaches and pedagogy literature; (2) opportunities for experiential learning, active learning, a multi-disciplinary learning community, and diversity and inclusion; and (3) the impact of the TD program on participants' career choices. Findings imply the need to develop TD programs that expose participants to multiple evidence-based pedagogies, and that weave in opportunities for experiential learning, interactive-workshop activities, and a learning community.