This paper premises that the movement to found Mechanics' Institutes in Britain during the 1820s and 1830s was informed by an interest in the social control of sectors of the working classes. However, the main task is the elucidation of the scheme of things which led those who projected the Institutes to believe that a scientific curriculum could effect the desired changes in values and behaviour. Advocates of popular scientific education deployed informal psychological models of the lower orders' mentality, and it was by reference to these imputed characteristics that a partly reified scientific curriculum was thought to have the power to produce stability of conduct. The paper concludes by attempting explicitly to relate this interpretation of Mechanics' Institutes to general problems faced by social scientists in relating knowledge to social interests.