This is randomized placebo-controlled clinical trial of a select population, with the core questions revolving around the impact of brief (11 week) treatment with citalopram, a selective serotonin reuptake inhibitor (SSRI) on hostility as measured a number of ways. Healthy individuals who score above the median on standard measures of hostility will be identified. While questionnaire measures will be used to screen and select individuals, a host of measures of hostility will be employed to more fully capture the wide ranging aspects of this "personality" dimension, and thereby better ascertain the impact of the active agent. In addition to the measurement of the central personality dimension of interest, a wide range of other factors are to be measured. Life style risk factors measured include (e.g., the use of salivary cotinine to assess the validity of participants' self-report regarding tobacco use, the use of unannounced 24 hour dietary recalls, the use of pedometer to assess physical activity), autonomic activity (e.g., the wide range of indices available through the use of impedance cardiography, the use of heart rate variability, baroreceptor sensitivity), and platelet activity.