Symptoms such as delusions, hallucinations, and thought disorder are the impairments of schizophrenia. These impairments can impede an individual's ability to perform certain skills and activities which, in turn, can limit the fulfillment of social and vocational roles. In view of the intrusion of symptoms of major mental disorders—delusions, hallucinations, depression, and anxiety—on the cognitive and interpersonal capabilities of afflicted individuals, it is not surprising that such impairments lead to significant disability and handicap. For example, unemployment has been found to be as high as 70 percent in the chronic mentally disabled (Goldstrom and Manderscheid 1982). Unemployment is a prime index of handicap since the demands of work in modern society accentuate the deficits, deviance, and stigma of mental patients. Employment rates following hospital discharge range between 10 and 30 percent, and only 10-15 percent of patients sustain their employment 1-5 years after discharge, with more recent studies revealing lower rates (Anthony et al. 1972; Anthony, Howell, and Danley 1984). Difficulties in work tolerance, endurance, following instructions, cooperating with co-workers and supervisors, problem solving, task orientation, sustained concentration, and ability to accept criticism and ask for assistance are all examples of disabilities that are caused by symptomatic and cognitive impairments and that lead to significant handicap. Thus, the impairments, disabilities, and handicaps of persons with psychiatric disorders are related to their psychiatric symptoms, and their vocational and social deficits. Symptomatic and functional problems exist on a continuum. For example, the nature of the illness can influence the severity and chronicity of the symptoms and social dysfunctions. Individuals with schizophrenia generally are more impaired and disabled than those with affective or anxiety disorders (Harrow et al. 1978). Within any one type of disorder, however, symptomatic and social-vocational course and outcomes vary considerably, both for different individuals and for the same individual over time (Liberman 1982a). Moreover, there are not always high correlations among the major dimensions of outcome of severe mental disorders; for example, social functioning may be adequate even in the face of poor vocational functioning and persisting symptoms (Anthony and Buell 1974; Buell and Anthony 1976; Anthony 1979). Alternatively, symptoms may persist but still permit adequate job adjustment (Strauss and Carpenter 1981; Anthony and Jansen 1984). The variability in the manifestations of major mental disorders is one of the most salient features of these disorders and can be best understood and studied through the interplay of vulnerability, stress, coping, and competence factors. The vulnerability-stress-copingcompetence model of major mental disorders explains the onset, course, and outcome of symptoms and social functioning as a complex interaction among biological, environmental, and behavioral factors (Liberman 1982b; Nuechterlein and Dawson 1984), and is congruent with the rehabilitation conceptualization. Psychobiological vulnerability may result in psychotic symptoms when stressful life events or ambient tensions in the family or work setting overwhelm coping skills. Vulnerability and stressors (- 1) are moderated in their impact on impairment, disability, and handicap by the presence and action of protective and potentiating factors. Prime among protective factors are coping and competence exercised by individuals, families, natural support systems, and professional treatment. Examples of protective factors include rehabilitation programs that offer skill building, social support, or transitional employment. Coping and competence can be attributes of the individual or of the social environment. From this point of view, an exacerbation or relapse of schizophrenic symptoms that accompanied use of street drugs of abuse (e.g., PCP, amphetamines) would result from the stressful action of these drugs on the individual's underlying biological diathesis for schizophrenia. In like manner, stressful life events (e.g., loss of a trusted therapist