This document discusses theories and models relevant to social and behavioral sciences in public health. It begins by defining the differences between theories and models, noting that theories are more formal and encompass broader domains while models apply to more narrowly defined behaviors. Four theoretical traditions are identified: social ecology, health promotion, interpretive studies, and critical perspectives. Specific intrapersonal, interpersonal, organizational, and multi-level models are then described in detail including the health belief model, social support theory, and diffusion of innovation theory. The document concludes by defining and providing examples of theories related to health and illness behavior.