The importance of psychological and social issues for children's well-being has long been recognized and their importance in the practice of pediatrics is well documented. However, many of the studies looking at this issue have emphasized psychiatric problems rather than issues commonly referred to as the new morbidity. The goal of this research was to refocus interest on the problems of the new morbidity. This study examined the rates and predictors of psychological problems in 19 of 23 randomly chosen pediatric practices in the greater New Haven area. Families of all 4- to 8-year-old children were invited to participate and to complete the Child Behavior Checklist prior to seeing a clinician. Clinicians completed a 13-category checklist of psychosocial and developmental problems based on a World Health Organization-sponsored primary care, child-oriented classification system. Of the 2006 eligible families, 1886 (94%) participated. Clinicians identified at least one psychosocial or developmental problems in 515 children (27.3%). Thirty-one percent of the children with problems received no active intervention, 40% received intervention by the clinician, and 16% were referred to specialty services. Not surprisingly, children whose problems were rated as moderate or severe were twice as likely to be referred compared with children with mild problems. Recognition of a problem was related to four characteristics: if the visit was for well child rather than acute care; if the clinician felt he or she knew a child well; if the child was male; and if the child had unmarried parents (all P less than or equal to .05).(ABSTRACT TRUNCATED AT 250 WORDS)