Smoking-related outcome expectation and self-efficacy have been found to be associated with adolescent smoking initiation. There is, however, a lack of appropriate instruments to investigate early adolescents' smoking outcome expectations and antismoking self-efficacy. The purpose of this study was to develop and validate the Smoking Outcome Expectation Scale (SOES) and Anti-Smoking Self-Efficacy Scale (ASSES). A total of 232 fifth and sixth graders from four elementary schools in Taiwan participated in the study. Both scales had good content validity, internal consistency, and test--retest reliability. On the basis of exploratory factor analysis, the 6-item SOES with two factors accounted for 54.72% of total variance and the 15-item ASSES with three factors accounted for 56.49% of total variance. The SOES had convergent and discriminant validity and ASSES had convergent validity. The two scales could help school nurses to understand early adolescents' smoking outcome expectation and antismoking self-efficacy and to develop more appropriate antismoking curricula.