Reducing smoking among adolescents is a public health priority. Affect, craving, and cognitive processes have been identified as predictors of smoking in adolescents. The current study examined associations between implicit attitude for smoking (assessed via the positive–negative valence implicit association test) and affect, craving, and smoking assessed using ecological momentary assessment (EMA). Adolescent smokers (n = 154; Mage = 16.57, SD = 1.12) completed a laboratory assessment of implicit smoking attitudes and carried a palm-top computer for several days while smoking ad libitum. During EMA, they recorded affect, craving, and smoking behavior. Data were analyzed using a multilevel path analysis. At the between-subjects level, more positive implicit smoking attitude was indirectly associated with smoking rate via craving. This association was moderated by positive affect, such that it was stronger for those with greater traitlike positive affect. At the event (within-subject) level, implicit attitude potentiated associations between stress and craving and between positive affect and craving. Individuals with a more positive implicit attitude exhibited more robust indirect associations between momentary stress–positive affect and smoking. In sum, a more positive implicit attitude to smoking was associated with overall levels of craving and smoking and might have potentiated momentary affect–craving associations. Interventions that modify implicit attitude may be an approach for reducing adolescent smoking.