Eye-hand coordination was investigated during a task of finger pointing toward visual targets viewed through wedge prisms. Hand and eye latencies and movement times were identical during the control condition and at the end of prism exposure. A temporal reorganization of eye and hand movements was observed during the course of adaptation. During the earlier stage of prism exposure, the time gap between the end of the eye saccade and the onset of hand movement was increased from a control time of 23 to 68 msec. This suggests that a time-consuming process occurred during the early prism-exposure period. The evolution of this time gap was correlated with the evolution of pointing errors during the early stage of prism exposure, in such a way that both measures increased at the onset of prism exposure and decreased almost back to control values within about 10 trials. However, spatial error was not entirely corrected, even late in prism exposure when the temporal organization of eye and hand had returned to baseline. These data suggest that two different adaptive mechanisms were at work: a rather short-term mechanism, involved in normal coordination of spatially aligned eye and hand systems, and a long-term mechanism, responsible for remapping spatially misaligned systems. The former mechanism can be strategically employed to quickly optimize accuracy in a situation involving misalignment, but completely adaptive behavior must await the slower-acting latter mechanism to achieve longterm spatial alignment.The human organism is able to adapt to many kinds of optical transformations of a visual scene. Since the end of the last century, a considerable amount of work has been performed on prism adaptation, especially on the locus of adaptation (see reviews in Koga, 1988;Kohler, 1962;Kornheiser, 1976;Welch, 1986). The different theories of prism adaptationcan be classifiedinto three main groups, based on the hypothesized nature of adaptation: arm proprioceptive change (Harris, 1963), central change in plurimodal coordination (Hardt, Held, & Steinbach, 1971; This work was supported by the Liaison Universite-Industrie, Rayonnement International, Lyon, France, the French Ministry of Research and Technology and Human Frontiers Science Program to Y.R., and by the grant in aid for developmental scientific research(6381002)from the Ministry of Education, Science and Culture of Japan to K.K. The authors are pleased to acknowledge Takara Tashiro, of Osaka City University, for providing the prisms used in this experiment, Hirokazu Yoshimura, of Kanazawa City University, for valuable comments about the experimental design and procedure, Kenji Susami, of Chukyo University, Nagoya, for his skillful help in the experimental hardware design and construction, Marc Jeannerod, and Claude Prablanc, of INSERM, Lyon, Alan Hein, of MIT, and Karen Reinkeof the University of Arizona, for thoughtful comments on the manuscript, and the voluntary subjects from the Department of Psychology, Nagoya University. We are especially indebted to an anon...