Ten replication studies based on quantitative procedures developed to measure motor and sensory/motor skill acquisition among handicapped and nonhandicapped infants and children are presented. Each study follows the original assessment procedures, and emphasizes the stability of interobserver reliability across time, consistency in the response measures, and informal comparisons of performance between handicapped and nonhandicapped infants. The following study topics and authors are included: visual fixation skills (C. Janssen); visual tracking skills (S. Komisar, C. Janssen); visual scanning skills (L. Vogt, C. Janssen); reach (J. Cutsinger, D. Esquith); grasp (C. Mears, D. Esquith); release (S. Courte, D. Esquith); transfer (M. Cisco, D. Esquith); head erect in the prone and supported sitting position in nonhandicapped infants (J. Rues); sitting behavior (C. Thompson, J. Rues); walking behavior (T. Foss, M. Noonan); and standing and sitting (E. Luddy, et al.). (CL)