In this paper, we present an analysis of the consequences of increasing density, over a period of nine years (from 1980 to 1988), on the dynamics, and the social and spatial organization of a forest roe deer population. Hunting of this population ceased in 1979, after which time there was a significant increase in population density, with three distinct periods easily identified: 1980–1983 (PI), immediately following cessation of hunting, characterized by a relatively low density (d = 5–7 animals/100 ha), 1984–1985 (P2), a period of rapid population growth, and 1986–88 (P3), a period of high density (d = 25 animals/100 ha). During PI, the population was irregularly distributed across the study site but, as density increased, distribution became more uniform, and eventually covered the whole of the available area. Home-range structure and shape remained unchanged from PI to P3 but, by the end of the study, average range size was 30% lower for adult males only, and the period prior to subadult males, but not females, establishing a permanent home range had increased from c. 18 month to c. 30 months. Winter group size increased overall from PI to P3 with, for the first time, observations of groups of five or more animals and a reduction in the frequency of observations of solitary females, with does more commonly observed in pairs or small groups; the proportion of solitary males, however, did not change between the two periods. The mean number of kids per female declined significantly from PI to P3 and body weights recorded for juveniles of both sexes and for adult males were also significantly lower during the period of relatively high density (P3). However, for adult females, absolutely no body weight change was observed. This divergence between the sexes of response to increasing density is discussed.