Although housing reform is generally associated with government programs enacted in the twentieth century, the concept of the slum ? a residential environment that degraded and harmed the poor ? and the basic responses to it originated one hundred and fifty years ago. In the mid-nineteenth century, changes in thinking about the formation of individual character, the importance of home life, spiritual redemption, the nature of poverty, the causes of crime and vice, and the sources of disease all converged to produce a moral environmentalist approach to the urban poor. The new concepts encouraged the idea that the physical disorder and dilapidation of the slums determined, or helped to determine, the physical and moral condition of their inhabitants. The notion that the environment influences the individual held out the possibility of creating an alternative environment that could nurture and improve the individual. To this end, housing reformers began in the 1840s to campaign for construction of better housing for the urban poor, the regulation of tenements and lodging houses, higher standards of sanitation, dispersal of slum dwellers to the suburbs and the country, and home ownership. Twentieth-century housing reformers have pursued similar goals, although often by different means, as ways to solve the problem of the slum.