The growth of research on social support has led to a comparable proliferation in the ways it is conceptualized and operationalized. The overall purpose of the present paper was to bring some clarity to this concept by critically examining how it has been presented in the literature and by proposing both rationally and empirically derived typologies for organizing social support functions. From a review of prominent discussions of support functions, a rational typology was proposed that included six categories: Material Aid, Behavioral Assistance, Intimate Interaction, Feedback, and Positive Social Interaction. To empirically examine the structure of social support, a factor analysis was conducted on items from a scale of socially supportive behaviors. The four factors that subsequently emerged were labeled Directive Guidance, Non-directive Support, Positive Social Interaction, and Tangible Assistance. Application of these findings to the assessment of support and future research on support/well-being relationships were discussed.