Weights and growth rates, feeding ecology, population ecology and social and spatial organisation of feral goats in the Southern Uplands of Scotland were investigated between 1977 and 1980. Seven populations were described as to their origins, breed type and management. In general, goats in the eastern populations were significantly larger than those in the western populations; those in the central populations were usually intermediate in size. This variation was probably related to variations in range quality.. Observations and faecal analyses showed that the feeding ecologies of goats and hill sheep, a potential competitor, were similar. In general, sheep used freely drained grasslands more and ate proportionately more grass than goats; the latter, possibly as a result of competition, ate more ferns, conifers, rica and rushes than the former. The very heavy use of ferns (bracken) by goats was discussed in relation to previous studies. Population size varied between c. 500 and c. 15 depending partly on the degree of culling. Billies, in general, had lower survival rates than nannies and together with kids their numbers varied within populations more than those of nannies. Reasons for the sex differential in survival and the variability in kid production were discussed in relation to reproductive behaviour, climate and population regulation. Group size varied in a predictable fashion with season, group type and population size. Complete sexual segregation did not occur but older billies tended to associate least with nannies, and especially so in the spring. Goats were spatially organised into hefts i. e. groups of individuals having highly overlapping home ranges; in general there was little overlap between heft home ranges and only billies moved between hefts and then predominantly at the rut. The ecology of feral goats was compared with that of other species with particular reference to the questions of dispersal and territoriality. Recommendations for improved management and future research concluded the thesis.