Structural equation models were used to test the effectiveness of various theories in predicting cigarette smoking among adolescents. Maximum-likelihood estimation, as implemented in LISREL for Windows 8.12, was used to compare the theory of reasoned action (TRA), the theory of planned behavior, and a modified version of the theory of reasoned action incorporating past behavior. Respondents consisted of 225 high school students who were questioned in 1994 about their attitudes, subjective norms, perceived behavioral control, past behavior, intentions, and actual behavior relating to the use of cigarettes. Results indicated that the modification of the TRA incorporating past behavior provided a marginally better fit than the other models. For this group of high school students, attitudes toward smoking, past behavior in relation to smoking, and perceptions of what significant others think they should do were significant predictors of their intentions to smoke. Intentions, together with past behavior, predicted their actual behavior. The models used in the present research show that this behavior can be explained with reference to a small number of key variables which are useful for furthering our understanding of the structure of adolescent smoking.