Creating effective bridges between science and society – especially with scientifically underserved groups – is increasingly recognized by scientists and engineers, as traditional educational venues (e.g., museums) do not reach everyone. With support from the National Science Foundation, we developed the STEM Ambassador Program (STEMAP) to guide scientists to draw upon both their research topics and their personal interests to engage community groups in the venues where they live, work, and gather. In our cohort-based trainings, “STEM Ambassadors” learn and practice skills to be responsive to the interests, values, and experiences of a specific “focal group” with whom they share common ground. Ambassadors build trust by demonstrating a willingness to listen and support the community. Over 95% of our 150 Ambassadors reported an increase in their interest and capacity to engage with new audiences, e.g., senior citizens, hunters, youth-in-custody, and faith-based communities. We now offer STEMAP to other institutions.