A proposed theory of planned behavior, an extension of Ajzen and Fishbein's (1980, Understanding attitudes and predicting social behavior. Englewood-Cliffs, NJ: Prentice-Hall) theory of reasoned action, was tested in two experiments. The extended theory incorporates perceived control over behavioral achievement as a determinant of intention (Version 1) as well as behavior (Version 2). In Experiment 1, college students' attendance of class lectures was recorded over a 6-week period; in Experiment 2, the behavioral goal was getting an “A” in a course. Attitudes, subjective norms, perceived behavioral control, and intentions were assessed halfway through the period of observation in the first experiment, and at two points in time in the second experiment. The results were evaluated by means of hierarchical regression analyses. As expected, the theory of planned behavior permitted more accurate prediction of intentions and goal attainment than did the theory of reasoned action. In both experiments, perceived behavioral control added significantly to the prediction of intentions. Its contribution to the prediction of behavior was significant in the second wave of Experiment 2, at which time the students' perceptions of behavioral control had become quite accurate. Contrary to expectations, there was little evidence for interactions between perceived behavioral control and the theory's other independent variables.