Military bases are like cities within cities. Both provide similar services, experience many of the same problems, and share the residential and working population of a region. Both occupy a limited footprint, while also creating impacts on land and other resources beyond their boundaries. Aligned interests around using limited space most efficiently and effectively create a natural opportunity for these communities—military and civilian—to partner on smart growth strategies. Through careful planning, active military bases can address concerns about urban encroachment, and communities can protect public safety and quality of life. Even when military bases close, communities may have unique opportunities to pursue smart growth goals, whether by planning a new community or enhancing an existing one. This issue summary reviews the issues faced by communities near military installations, and summarizes leading practices in dealing with encroachment and base reuse challenges.