User-cooperation represents an effective way of introducing diversity in wireless networks. Spatial diversity gains are obtained through the cooperation of mobile users and the use of the partner's antenna. In this paper, we design channel codes that are capable of achieving the full diversity provided by user-cooperation, with the constraint that they also provide the best possible performance in the noncooperative case. The codes continue to perform well, even when the interuser channel is noisy, still offering significant improvements with respect to the noncooperative case.