The purpose of this article is to examine the relationship between rat
ed and measured activity in children. Activity level is a theoretical
component of temperament, and empirical studies of child behavior diso
rder consistently reveal hyperactivity as a behavior disorder. This ar
ticle demonstrates that the Conners Teacher Rating Scale, Motor Excess
subscale of the Revised Behavior Problem Checklist, and the Nervous-O
veractive subscale of the Child Behavior Checklist-Teacher Rating Form
are significantly and substantially intercorrelated, thereby supporti
ng their construct validity. Additional large significant correlations
between all three ratings and measured activity (steps per hour) furt
her support the concurrent validity of activity ratings by teachers. H
owever, important discrepancies exist between rated and measured activ
ity for a substantial proportion of the boys. This finding strongly su
ggests that a second opinion be obtained through a 2-week behavioral s
ample using an activity measuring instrument, especially when concern
exists over excessive activity prior to reaching diagnostic and/or tre
atment conclusions.