Personality traits may be more influential to participation than demographic, professional, or socioeconomic determinants. Word-of-mouth recruitment appears to underlie the increase in STMM activity, facilitated by information technology. Reported key motivators for physician participation in STMMs tend to parallel schools of thought regarding philanthropy and volunteering and include satisfaction from helping in challenging conditions of limited resources, learning experiences, appreciation from patients, sense of renewal, and the legacy effect of teaching.