The urpose of the study was to establish developmental norms for maternalratef problem behaviors within a disadvantaged group of preschool children. The sample included 406 children between two and five years of age from lower socioeconomic families. Mothers completed the Behavior Problem Checklist (BPC) reporting the frequency of conduct (acting-out ) and personality (inhibition) problems. The analyses investigated differences for males and females among four age groups for fre uency of behavior problems. No significant age differences were found for ei&er sex on the acting-out or inhibition dimensions of the BPC. The results revealed that the frequency of behavior problems becomes apparent at an early age and iemains consistent throughout the preschool years. The consistency across age levels of these maternal-reported behavioral difficulties suggests that early screening with BPC is a viable procedure. The data are discussed in terms of their utility in assisting the school psychologist, to select appropriate intervention strategies for the preschool child.There has been increased pressure in recent years for school psychologists to become more involved in the assessment of preschool children. The increased attempt to identify preschool children who are "at risk" with respect to educational failure has been necessitated by law (Education of the Handicapped, PL 94-142) and promoted by increased money for employing additional school personnel specializing in preschool assessment. With the increased emphasis on identification of preschool children a t risk for educational problems, renewed attention is focused on the consistency across the preschool age range of various screening or readiness tests. The consistency of screening measures is of considerable importance, since they directly affect the efficacy of various intervention strategies. While there has been considerable emphasis in most preschool assessment batteries on intellectual, language, perceptual-motor, and developmental skills, there has been minimal information regarding objective measures of behavior. Furthermore, the majority of screening techniques have focused on information obtained directly from the child during an evaluation session (Jansky & DeHirsch, 1972). Such preschool assessment batteries include behavioral observations during readiness screening or a brief questionnaire regarding developmental maturity. However, there is a dearth of information regarding attempts to objectively identify behavioral dimensions which might prove valuable in identifying children at risk regarding future educational failure.It is surprising that research on objective measures of preschool behavior has been relatively neglected, since acting-out vs. withdrawal behavior has been shown to have considerable continuity over time (Bayley & Schaefer, 1964;Eichorn, 1973;Peterson, 1961) and to be significantly related to later school achievement (Kohn & Cohen, 1975). One reason for the infrequent use of objective behavior ratings with preschool cbildren may be the ...