This article reviews the Conners Early Childhood (Conners EC; Conners, 2009), a behavior and development rating scale intended to assess children in early childhood, specifically defined as ages 2 to 6 years. Using multiple informants across multiple settings, the Conners EC is administered for the purpose of early identification of disorders or developmental delays, screening, and planning and monitoring interventions for preschool-aged children. Although the assessment is designed to be administered individually, instructions are included to accommodate group screening. The assessment utilizes parent report (191 items) and teacher/caregiver-report (187 items) forms to facilitate a multi-informant approach that comprehensively captures a child's behavior. The article describes the Conners EC in the areas of scoring, test materials and manuals, technical adequacy, and reliability and validity. It finds that the Conners EC reliably measures age appropriate behaviors and developmental milestones, and functions well as a screening measure of general behavioral or cognitive impairment. Overall, the Conners EC demonstrates a significant array of strengths, including good reliability and high validity for the purposes and populations it is intended to measure.