The objectives of this project are (I) to evaluate the influence of age and sex on alcohol elimination rates in men and women, and (II) to determine the influence of age and sex on the initial response and acute adaptation to alcohol on measures of subjective perceptions of alcohol effects and heart rate. This study will be conducted in 24 young and 24 older participants, with equal numbers of males and females in each group. Comparison of alcohol elimination rates across these groups and correlation with liver volume and sex steroid levels will provide a means to examine the influence of sex hormones, estrogen and testosterone, in age-related and sex-related differences in alcohol metabolism and liver volume. This study will examine age- and sex- related differences in response to alcohol on subjective measures of intoxication and mood, as well as on heart-rate and psychophysiological responses to emotional visual stimuli (pictures). This study will also evaluate the effect of acute alcohol administration on gene expression in peripheral blood cells. Findings from these studies will provide important new data regarding the role of sex steroids (estrogen and testosterone) on the metabolism of alcohol, and a better understanding of age- and sex-related differences in metabolic processes that may underlie medically important differences in the responses of individuals to alcohol.