Briefly considering the literature, this paper reviews research in the area of temperament and points out the implications of findings for school psychologists. Following a brief discussion of several definitions of temperament, two issues given the most consideration in the theoretical literature are outlined: the genetic origins of temperament and the stability of temperament over time. A brief summary of empirical evidence bearing on both issues is presented. Next, research is reviewed which is devoted to the development of measurement devices for assessment of temperamental characteristics in infants, toddlers, preschool and elementary children, middle-school children, and adults. Finally, a selected review of current research examining the effects of temperamental differences on such areas as the development of psychopathology, school adjustment, intelligence, and academic achievement are summarized and discussed. (MP)