We explore how avatars can be used as social orthotics defined as therapeutic computer-based social companions aimed at promoting healthy behaviors. We review some of the health interventions deployed in helping at-risk populations along with some of the unique advantages that computer-based interventions can add to face-to-face interventions. We posit that artificial intelligence has rendered possible the creation of culturally appropriate dialog-agents for interventions and we identify specific features for social avatars that are important - if not necessary - when applied to the domain of social orthotic systems for health promotion.