A considerable body of evidence demonstrates that active, student-centered instructional practices are more effective than lecture-based, transmissionist approaches in improving undergraduate STEM learning. Despite this evidence and extensive reform initiatives, the majority of STEM instructors continue to teach didactically. Awareness of teaching innovations is widespread in some STEM disciplines, and instructors report trying new instructional approaches, yet the majority of them fail to continue using active learning strategies. Recent work suggests that the decision to experiment with and persist in using a teaching innovation is influenced more by instructors' perceived supports (e.g., access to curricular resources, supportive colleagues, positive departmental climate toward teaching) than perceived barriers. This commentary expands on the notion that the instructional decision-making process is personal and influenced by both individual and contextual factors to explicitly model the potential mechanisms by which peers encourage or discourage adoption of teaching innovations. We also discuss implications of this work for future research. We hope that this model will be helpful for work related to increasing the prevalence of active, student-centered instruction in undergraduate STEM.