Although much research has focused upon why people do and do not engage in recommended health behaviors, there is a need to develop more accurate theories to explain and predict engagement in health behaviors. Because health behaviors differ in important ways, it could be most fruitful to understand one type of health behavior, such as secondary prevention behavior. This paper proposes a theory of care-seeking behavior (CSB), based on a theory of general behavior by Triandis. Other popular theories about health behavior (i.e., Health Belief Model and Theory of Reasoned Action) also are reviewed. Empirical support for the variables identified in the theory of CSB is presented, drawing from the literature on secondary prevention for cancer. The theory of CSB is applied to the situation of seeking care for cancer symptoms. Directions for future research based upon this theory are delineated.