Gender differences in preschool children's activity level were investigated using archival data, consisting of temperament questionnaires and an open-ended interview. Parents of 63 preschool students ranging in age from 3 to 6 years completed the Temperament Assessment Battery for Children (TABC; Martin, 1988), the Colorado Childhood Temperament Inventory (Rowe & Plomin, 1977), and the Children's Behavior Questionnaire (Rothbart, Ahadi, Hershey, 1994). Teachers completed the TABC. The Structured Temperament Interview (Teglasi, 1994) was administered to both teachers and parents. Results support conceptualization of activity level as comprised of two factors: motoric movement and modulation. Mean gender differences were due to differences in frequency of boys and girls at the extremes of activity level continua. Qualitative analyses indicate parents and teachers conceptualize activity level similarly for both genders, and that low modulation of activity level is maladaptive in preschool children. Implications for the measurement of activity level and intervention development are discussed.