This study examined the structure and determinants of lay people's implicit theories of heroin addiction. A questionnaire was derived from interviews with lay people about their beliefs and theories of heroin addiction and academic literature on the subject. One hundred and forty-four subjects completed the questionnaire, in which they rated 105 statements about the causes, correlates and cures of heroin addiction. The three parts of the questionnaire were individually factor analyzed and a clear, interpretable factor structure emerged for each. The factors seemed similar to explicit academic theories, but the exception was beliefs about cure, which did not show overall support for the most clinically used models. When the three factor analyses were combined into a single 'higher-order' factor analysis four factors emerged, labelled moralistic, psychosocial, sociocultural and drug treatment, which reflect more or less coherent views on the nature of heroin addiction. Subjects' political beliefs was the greatest (demographic and attitudinal) determinant of lay beliefs in these factors, with experience of addiction, addicts, drugs and age also highly correlated. Vote was the main determinant and best predictor of the four 'higher-order' structured lay theories: right-wing voters emphasizing moralistic and individualistic theory and left-wing voters supporting the psychological and societal ideas. Implications for policy and interventions to addicts of these lay theories are considered. Copyright (C) 1996 Elsevier Science Ltd
