Changes in the time for adjustment to a displacement prism with repeated exposure show that this is skill acquisition. We measured times for rapid reaches to place a stylus in a target. Participants wearing a prism worked to achieve criterion times established without the prism. Blocks of trials with and without a prism were alternated. Number of trials to criterion, mean times per block, mean first trial times within blocks, and a measure of the response to perturbation by prismatic displacement decreased gradually over blocks in a session, as well as over three days. By the third day, participants were able to respond immediately to perturbations. The immediacy of adjustment transferred partially to reaches with a larger prism. This skill must be similar to that acquired by users of corrective lens.