STEM undergraduate education reforms are more likely to be effective if undertaken not by individual faculty members but by faculty networks or "communities of transformation." The article describes four such communities that have persisted over many years and served large numbers of faculty through annual events, newsletters and journals, curricular materials, and sub-groups on more focused topics or made up of faculty who are geographically close to one another. The "community" embodies a philosophy (e.g., a focus on large questions of civic importance, active and experiential learning, or problem-based learning) that participants value highly with outcomes for individuals (e.g., learning and improving practice, feeling reenergized, getting recognition for pedagogical work, developing leadership skills) and for participating departments and institutions (e.g., curricular changes and strategic planning for science education). Female faculty and faculty of color reported significantly greater gains in credibility and the skills that lead to advancement from participation in those communities.