Previous research has demonstrated that informant disagreement is common with the use of rating scales to assess problem behavior in school-age populations. However, much less is known about this phenomenon in preschool populations. This is important because the accurate assessment of problem behavior in preschool is complex due to the rapid developmental shifts during this period. As such, the purpose of this study was to assess the prevalence of students at risk of behavior problems and to see whether these problems varied as a function of informant and ecological characteristics. Using the Behavior Assessment System for Children--Second Edition, we analyzed parent and teacher ratings for 320 preschool children. Results indicated that parent and teacher ratings were very similar, with males being rated as more at risk of having attention problems and social skill deficits in comparison with females. No differences were noted in at-risk status by ethnic group membership. Conversely, significant and consistent parent and teacher ratings were noted by socioeconomic status (e.g., parent education level). Implications are discussed for the prevention of problem behavior in preschool. (Contains 3 tables.)