Few studies have considered whether psychological determinants of nonsmoking among college students vary by ethnicity. The authors tested the theory of planned behavior (TPB) to explain differences in nonsmoking intentions of 238 African American and 197 Caucasian college students who completed an in-class TPB questionnaire and a smoking assessment 1 week later. After removing 35 students who reported smoking at the baseline assessment, regressions were used to examine ethnic effects on TPB constructs when predicting nonsmoking intentions. Caucasians had statistically significant higher nonsmoking intentions than African Americans. Further, subjective norms for Caucasians and attitudes for African Americans had small but significant relations to intention, but perceived behavioral control (PBC) was a strongly significant predictor for both ethnic groups. However, the prediction of nonsmoking intentions was not statistically moderated by ethnicity for any of the TPB constructs. This study suggests that the TPB may aid in understanding collegiate nonsmoking intentions and help begin to explain differences in smoking on the basis of ethnicity. Last, because of strong associations shown in this study, PBC should be considered when developing ethnic-specific smoking interventions in college students. (Contains 2 tables.)