Rating scales are designed to both complement and supplement traditional performance-based measures. Both can provide useful information about the functioning of youth with histories of prenatal alcohol exposure. Few studies, however, have compared ratings from multiple informants or the relationship between these subjective rating scale scores and the objective results from laboratory performance-based scales. The current study addressed both of these questions in three study groups: children with histories of prenatal alcohol exposure (AE; n = 47), attention deficit/hyperactivity disorder (ADHD; n = 41), and typically developing controls (CON; n = 73). Subjects ranged in age from 8 to 16 years (M = 11.8, SD = 2.5) and were recruited from five different sites across the United States. All subjects completed a standardized neuropsychological test battery, including laboratory measures of executive functioning as well as a self-report measure of executive function behaviors. Parents and teachers completed corresponding rating scales of executive function behaviors for each subject. This study assessed the relationship between these behavior rating scales and corresponding neuropsychological tests, as well as inter-rater agreement among the multiple informants. All correlations were examined for each rater and each group separately. Few significant correlations were found between the rating scales and laboratory measures, and inter-rater agreements differed by group. Inter-rater agreement was found between parent and teacher ratings for children with prenatal alcohol exposure, whereas teacher child agreement was found for those with ADHD. Findings from this study indicate that behavior ratings can be used to supplement laboratory measures and may be measuring different aspects of executive functioning abilities. A multi-method approach should be used when measuring skills in this domain. This was one of the first studies to examine cross-informant agreement in a sample of children with prenatal alcohol exposure, and further research is necessary to understand why inter-rater agreement differed for children with prenatal alcohol exposure and those with ADHD.