The variety of methods available for the assessment of hyperactivity in preschool populations is described. A multidisciplinary perspective, integrating biophysical, behavioral, cognitive, and ecological models of assessment, is used to structure and guide the review. This perspective reflects the need for a comprehensive and multidimensional approach when assessing the heterogeneity of behaviors associated with hyperactivity in young children. Issues related to the identification of hyperactivity among preschool children are also discussed.Conceptual models represent features of a presenting problem that are believed to be essential for the understanding of the difficulty, and serve to organize information in a focused and comprehensible format. In the study of hyperactivity, the use of a conceptual model is especially critical because of the massive numbers of explanations, assessment alternatives, and suggested interventions reported in the professional literature. Without such an organizational structure, it would be easy to be overwhelmed by the diversity of orientations to this childhood disorder. The purpose of this paper is to identify and describe the variety of procedures available for the assessment of hyperactivity in early childhood (preschool children between 2V / 2 and 6 years of age). A multidisciplinary perspective has been developed to organize our review. Following a brief discussion of the characteristics of preschool children with hyperactivity, the various components of this perspective will be detailed. The perspec TECSE 9(1), 90-105 (1989)