Tobacco use remains the leading cause of preventable death in the United States, and there is a need for new interventions for tobacco dependence. There has been increasing interest in developing interventions that directly target attentional processes. In attentional re-training (AR), cognitive experimental paradigms are re-designed so that they can actually modify (rather than simply measure) attentional processes. Hitherto, researchers have administered AR in the laboratory or over the internet. We will investigate the efficacy of AR administered on a Smart Phone multiple times per day. Adult smokers (N = 144) who wish to quit smoking will enroll in a study examining the effects of AR on attentional bias, craving, and smoking. They will be randomly assigned to either an AR group or a control group. They will be given a Smart Phone to carry around with them for 21 days prior to their scheduled quit day, and for 21 days after their scheduled quit day. Participants will be scheduled to complete AR (or control) tasks 3 times per day. In addition, participants will complete two attentional bias tasks (visual probe task and modified Stroop task) per day on the Smart Phone both pre- and post- quit. All participants will receive individualized smoking cessation counseling. The Specific Aims are to examine whether AR (delivered on a Smart Phone) can: 1) reduce attentional bias to smoking-related stimuli in smokers wishing to quit; 2) reduce craving in smokers wishing to quit; and 3) reduce smoking.