This report presents the proceedings of a working group convened in Copenhagen in November 1975 by the World Health Organization to discuss the problems of children 5 to 9 years. The report focuses on a survey of the general problems of European children of this particular age, individual risk factors, and individual groups at risk, and suggests possible solutions to these problems. A review of the characteristics of children aged 5 to 9 considers relevant geographical population statistics, physical health and development, cognitive development, psychosocial development, and the growing involvement of the 5- to 9-year-old in the community outside home and school. A discussion of the problems of 5- to 9-year-olds comprises the largest section of the report. General problems which arise as a result of technological advances in society, urbanization, changing family structure, family migration within and between countries, unemployment, and other socioeconomic changes are briefly touched upon. Individual risk factors such as nutritional problems, infectious diseases, accidents, chronic diseases, and slow learning problems are described in detail. Environmental risk factors such as stress resulting from initial entry into school, urbanization, and non-optimal social and economic conditions are also discussed. Potential solutions are discussed in detail and recommendations based on the report are summarized. (CM)