What are the antecedents to the usage of online health-based support groups? This article draws on the motivation literature to posit the role of disposition-specific and situation-specific motivations in shaping the use of online health support groups. Based on 2 different nationally representative studies, it examines the role of situation-specific and disposition-specific motivations as predictors of online health community participation. Study results point out that intrinsic health orientation is a positive predictor of participation in an online health community. In addition, disease-specific motivation in the realm of perceived susceptibility to a disease or being detected with a disease triggers online community participation in disease-specific groups. The study results provide theoretical and practical guidelines for future scholarship.