Smoking is the most preventable cause of death in the United States. Most adult smokers began smoking during adolescence, making youth tobacco prevention an especially important public health goal. Guided by an extension of the theory of planned behavior (TPB), this study examined the role of psychosocial factors in accounting for adolescents' smoking intentions. Participants from three high schools (n = 785) were surveyed to assess smoking-related characteristics and behaviors as part of a statewide evaluation of tobacco prevention programming. Attitudes, subjective norms (and other normative factors) and perceived behavioral control were all associated with non-smokers' intentions to smoke. Having more favorable attitudes toward remaining tobacco free and perceiving that friends would not be supportive of smoking were both associated with decreased likelihood of intending to smoke. Normative influence and peer use were significant factors, such that having more friends who smoke was associated with increased odds of intent to smoke. Lastly, perceived difficulty to quit was related to smoking intentions, with higher confidence to quit significantly associated with intentions to smoke. Findings are consistent with the TPB--attitudes, normative factors and perceived behavioral control each helped account for non-smoking adolescents' intentions to smoke. Implications for theory and intervention building are discussed. (Contains 4 tables.)