• Associations between two measures of physical fitness, 1.6-km run/walk performance and sum of three skinfold thicknesses, and selected physical activity factors were studied in a nationally representative sample of third- and fourth-grade students (1150 boys, 1202 girls). Twenty physical activity variables measured via parent and teacher questionnaires were factor analyzed, and for each of the resultant eight factors, individual factor scores were generated. These were used in two multiple regression analyses in which 1.6-km run/walk time and sum of skinfold measurements were the dependent variables. Multiple R2 for these two analyses were .21 and .18. Significant factors in both analyses were global ratings of the child's activity level, age, vigorous community activities, and gender. The results indicate that physical activity and physical fitness are significantly, although moderately, associated in young children and suggest that interventions directed toward enhancement of physical activity in children are worthy of investigation.