The stressor reactivity measures from the NPU task will be tested as predictors of clinical outcome (i.e., continuous abstinence during the two-week cessation period) to evaluate the validity of each as surrogate endpoints for use in research on stress mechanisms in smoking relapse. Deprivation status at the time of the NPU stressor task will be examined as a moderator of the effect of stressor reactivity to determine if the surrogate endpoints predict clinical outcome generally or only as deprivation increases.