AIM: To describe an evidence-based model for preventive child health care and present some findings from baseline measurements. METHODS: The model includes: parent education; methods for interaction and language training; follow-up of low birthweight children; identification and treatment of postnatal depression, interaction difficulties, motor problems, parenthood stress, and psychosocial problems. After baseline measurements at 18 mo (cohort I), the intervention was tested on children from 0 to 18 mo at 18 child health centres in Uppsala County (cohort II). Eighteen centres in other counties served as controls. Two centres from a privileged area were included in the baseline measurements as a "contrasting" sample. Data are derived from health records and questionnaires to nurses and mothers. RESULTS: Baseline experiment (n = 457) and control mothers (n = 510) were largely comparable in a number of respects. Experiment parents were of higher educational and occupational status, and were more frequently of non-Nordic ethnicity. Mothers in the privileged area (n = 72) differed from other mothers in several respects. Experiment nurses devoted considerably fewer hours per week to child health services and to child patients than did control nurses. CONCLUSIONS: Despite certain differences, experiment and control samples appeared comparable enough to permit, in a second step, conclusions about the effectiveness of the intervention.