Since January 1969, a systematic health screening has been offered to 4-year-olds resident in the county of Uppsala, Sweden, at the ordinary Child Health Centres by the regular staff. This report describes some organizational and methodological aspects and presents participation rates and reasons for non-participation. From the overall experience it is concluded that the program is feasible with respect to systematic examinations and data collection, acceptance by the public and the staff, and with respect to the strain on existing resources. The reasons for and the importance of program changes are discussed, and the main advantages and drawbacks of the decentralized approach are mentioned. Finally, a theoretical framework for a quantitative evaluation of effectiveness is presented.