BackgroundWe test the hypothesis that negative attitudes to mentally ill people may be fuelled by a lack of knowledge.MethodA census of knowledge of mental illness was conducted in two areas prior to the opening of long-stay supported houses for the mentally ill in each area. Three attitudinal factors (Fear and Exclusion, Social Control and Goodwill) which had been extracted by factor analysis of the Community Attitudes toward the Mentally III (CAMI) inventory (see previous paper) were analysed in respect of their associations with knowledge of mental illness.ResultsMost respondents (80%) knew of somebody who had a mental illness but a substantial proportion of respondents had little knowledge about mental illness. Social Control showed an association with knowledge of mental illness. Groups who showed more socially controlling attitudes (especially those over 50 years old, those of lower social class, and those of non-Caucasian ethnic origin) had less knowledge about mental illness. Regression analysis revealed that when knowledge was taken into account age had no effect on Social Control, and the effect of social class and ethnic origin was diminished Respondents with children, who showed more Fear and Exclusion, were not less knowledgeable about mental illness.ConclusionsThe results support the hypothesis that negative attitudes, especially in older people, are fuelled by a lack of knowledge. Negative attitudes among people with children are not related to a lack of knowledge.