The thesis consists of seven Sections. Each Section contains a set of published papers, reports or chapters which describe epidemiological aspects of the Cerebral Palsies (CPs). These have, in the main, made use of of the Western Australian Cerebral Palsy Register. Several of the chapters are from a recent book (Stanley and Alberman, 1984), which was an invited monograph in a series published jointly by Spastics International Medical Publications and Blackwells, Oxford. The published work in each Section is introduced and moulded together by text with the aim of making it flow as a composite whole. The numbers and rates differ between papers as the register is continually being updated and recent figures are more accurate and complete than in earlier publications. The Register was established in 1977, with the aims of being basically descriptive: to provide accurate numerator data on the major cause of childhood motor handicap. In addition it was planned to utlisie the data base as a population sampling frame for epidemiological studies searching for causes of the CPs. It is now an ongoing collection and it is the only population-based Cerebral Palsy Register in Australia. Four others exist in the world, one in Denmark (Hansen, 1960; Glenting, 1976), one in Sweden (Hagberg et al., 1975a, 1975b, 1976), one in County Cork, Ireland (Cussen et al., 1978), and one in Newcastle-Upon-Tyne in UK (Hey, personal communication). It is of considerable current interest, as paediatric research is expanding into the causes of childhood handicaps generally, and perinatal researchers are keen to monitor the trends of major handicap in relation to changes in perinatal care.