This special online issue of Psychological Services, dedicated to Congressman John Lewis, includes 16 articles that describe the efforts to further behavioral health advocacy in public service settings. Advocacy, an ethical imperative for psychologists, can take many forms. Unfortunately, there are myriad barriers to routine advocacy for numerous issues pertinent to public service settings. Thus, attention must be drawn to the nuances of conceptualizing, implementing, and evaluating this work. The articles in this special issue address behavioral health advocacy from multiple vantage points. This includes articulating theoretically-informed approaches to advocacy, training models for behavioral health advocacy, advocacy for specific populations and settings relevant to public service psychology, and descriptions of psychologist's experiences engaging in such advocacy. Taken together, these articles highlight "lessons learned" including ways to overcome barriers encountered, which hopefully will help inform other burgeoning and ongoing advocacy endeavors in public service settings. This introduction underscores the unique contributions of these articles and summarizes the overarching themes related to the state of behavioral health advocacy work in public service settings. The articles capture innovative and significant behavioral health advocacy efforts in public service settings and lay the groundwork for future collaboration among psychologists and other behavioral health professionals invested in advancing advocacy in these contexts.