PROJECT SUMMARY (See instmctions): It has become increasingly clear that young adulthood represents a fime of heightened vulnerabiliy to smoking progression and development of nicofine dependence. Nonetheless, the mechanisms underiying smoking behavior in this age group are sfill not well understood. Given that the majority of adult smokers smoke as a means of regulating affect, inlcuding negafive affect attributable to withdrawal, the present study proposes to assess, under controlled laboratory conditions, the effect of smoking and nicofine on affective response in young adult smokers. Similar experimental approaches have been used to great effect with other drugs of abuse, yet suprisingly, other than our own previous work in this area, few empirical invesfigafions have assessed both nicofine administrafion and deprivation effects on emotional response in young adults. Knowledge of such effects is crucial to furthering our understanding of the processes governing development of nicotine dependence, as well as to assess individual differences in the manifestation of withdrawal and smoking effects on emotional response. Toward these ends, the proposed laboratory study will examine the acute effects of cigarette smoking and nicotine on emofional response and working memory capacity in 147 young adult smokers. Participants will attend three randomized laboratory sessions during which they will: smoke a nicofine cigarette, smoke a denicotinized cigarette, and not smoke (deprivation condition). Hence, this study design will allow for fine-grained assessment of acute smoking, nicofine, and deprivation effects. A mulfidimensional approach to the measurement of emofion will be used, drawing upon self-report measures of positive and negative affect, heart rate, skin conductance, fearpotentiated startle eyeblink response, and facial electromyography (zygomatic and corrugator muscle groups). Standardized measures of craving will also be employed both within and across the three sessions. Finally, because nicofine administrafion is thought to increase working memory in adult smokers, and deprivafion, reduce it, a well-validated task measuring working memory capacity will also be employed. Assessment of individual differences in these respective variables will also allow for assessment of whether such differences are predictive of future smoking behavior.