All the papers about flat dwelling (Central Housing Advisory Committee, 1952; Hopper, 1962; Hird, 1966; Fanning, 1967; Gunn, 1968; Gilloran, 1968 and Stewart, 1970) except one (Sheerboom, 1962) state that it has an adverse effect on mental health. They are almost unanimous in naming the care of children as a cause. The best study from a scientific point of view (Fanning, 1967) showed a significantly higher rate of psychiatric consultations among those living in the same flats as in the present study. This was thought to be due to social isolation caused by the nature of the flats and being confined in them by children. A widely held belief that bad housing can cause or aggravate mental illness is not justified by the evidence. Three investigations (Martin, Brotherston and Chave, 1957; Wilner, Walkley, Schram, Pinkerton and Tayback, 1960 and Hare and Shaw, 1965) failed to show any benefit to mental health from new housing. The only one (Taylor and Chave, 1964) to find an improvement studied new housing which was socially planned. All four studies failed to allow for two other variables. One was the adverse effect of the move itself (Maule and Martin, 1956; Hall, 1964 and Shepherd, Cooper, Brown and Kalton, 1966) on those in new housing. The other was moving to better old housing among controls (Wilner et al., 1960).