Individuals increasingly rely on healthcare virtual support communities (HVSCs) for social support and companionship. While research provides interesting insights into the drivers of informational support in knowledge-sharing virtual communities, there is limited research on the antecedents of emotional support provision and companionship activities in HVSCs. The unique characteristics of HVSCs also justify the need to reexamine members’ voluntary provisions of help in such communities. This paper develops a model that examines the relationships between the structural, relational, and cognitive dimensions of social capital and the provision of informational and emotional support, and engagement in companionship activities in HVSCs. The model is tested based on data generated through an automated method that classifies and analyzes user-generated text in three healthcare virtual support communities (breast, prostate, and colorectal cancer). The results show that all three dimensions of social capital impact the provision of emotional support; both structural and relational capital facilitate engagement in companionship activities; and only cognitive capital enables the provision of informational support. Research and practical implications on the need to facilitate informational and emotional support provision and companionship activities in healthcare virtual support communities are discussed.