Bipolar disorder has been conceptualized as an outcome of dysregulation in the behavioral activation system (BAS), a brain system that regulates goal-directed activity. On the basis of the BAS model, the authors hypothesized that life events involving goal attainment would promote manic symptoms in bipolar individuals. The authors followed 43 bipolar I individuals monthly with standardized symptom severity assessments (the Modified Hamilton Rating Scale for Depression and the BechRafaelsen Mania Rating Scale). Life events were assessed using the Goal Attainment and Positivity scales of the Life Events and Difficulties Schedule. As hypothesized, manic symptoms increased in the 2 months following goal-attainment events, but depressed symptoms were not changed following goal-attainment events. These results are congruent with a series of recent polarity-specific findings.Bipolar disorder exacts a devastating toll from affected individuals. Most strikingly, this disorder leads to suicide in almost one out of every five diagnosed individuals (Isometsa, 1993). With adequate blood serum levels of lithium, one third of bipolar individuals relapse within 3 years (Keller et al., 1992), but in naturalistic studies with varied levels of patient compliance, two thirds of patients relapse within 2 years (Silverstone, McPherson, Hunt, & Romans, 1998). Given these high rates of relapse and the sustained unemployment rates following each episode of mania (Harrow, Goldberg, Grossman, & Meltzer, 1990), it is not surprising that bipolar disorder has been ranked as the sixth leading cause of disability among both physical and psychiatric disorders worldwide (Murray & Lopez, 1996). Fiscal costs for adult Americans with the disorder were estimated in 1991 at $45 billion (Wyatt & Henter, 1995).Although the modal course is severe, bipolar individuals experience substantial heterogeneity in symptom expression. For instance, as many as 25% of bipolar I individuals will never experience a depressive episode (Goodwin & Jamison, 1990). Further, whereas some individuals experience daily shifts between episode poles, others remain well for a decade or longer (Angst, 1984).For many years, biological models have dominated attempts to understand this heterogeneity. The importance of genetic influences for this disorder is supported by findings of a concordance rate of .84 for monozygotic twins compared with .35 for dizygotic twins among 110 twin pairs (Bertelsen, Harvald, & Hauge, 1977); similar findings have emerged across 12 twin studies (Vehmanen, Kaprio, & Loennqvist, 1995).Beyond the important role of genes, the psychosocial environment appears to be a trigger of episodes. For example, expressed emotion (Miklowitz et al., 1988), social support (Johnson, Winett, Meyer, Greenhouse, & Miller, 1999), and life events (Ellicott, 1989;Johnson & Miller, 1997) each have been shown to predict symptom changes in bipolar disorder. Recent models of bipolar course have incorporated biological and psychosocial variables (cf. Goodwin & Jamison, 199...