Foot orthotics have proven to be an effective means of reducing clinical symptoms in the lower limb. Kinematic studies of runners have substantiated these findings by showing significant changes in a number of parameters describing foot function. This study examines the effect of foot orthotics during the loading response of walking, the period of stance when angular movements and positions of the calcaneus typically attain peak values. Twenty subjects exhibiting a minimum of 5 calcaneal eversion in static stance volunteered for this study. A musculoskeletal examination of the lower limb was performed on all subjects and rigid orthotics were fabricated based upon the findings. All subjects participated in both the orthotic and no-orthotic treatment conditions. A VlCON three-dimensional motion analysis system with a force platform was used to collect data. A MANOVA procedure was used to perform statistical analysis on the multiple dependent variables. Results showed significant changes in the following variables: 1) maximum calcaneal and calcaneal eversion angles, 2) total rearfoot movement, 3) height of the ankle joint center when both the maximum calcaneal angles occurred, 4) minimum height of the ankle joint center, 5) mediolateral lever arm of the point of application of the ground reaction force when both the maximum calcaneal angles occurred, 6) maximum eversion moment due to ground reaction, 7) maximum calcaneal and calcaneal eversion angular velocity, and 8) maximum calcaneal eversion and tibia vara angular acceleration. J Orthop Sports Phys Ther 1990;11(7):301-312.