The somatosensory system of adult primates is capable of considerable reactivation after the loss of some of the activating connections This chapter examines what happens when damage occurs at each of four levels of the system: the receptor or primary afferent level, the level of the brain stem relay to the dorsal column-trigeminal complex, the thalamic ventroposterior nucleus, and primary somatosensory cortex. It summarizes several important features that relate to plasticity. The chapter discusses the consequences of a nerve crush with regeneration, a nerve cut and repair with regeneration, a nerve cut without regeneration, and transplanting and regenerating a nerve to a new skin location. The clear evidence for extensive reorganization came with the opportunity to study the somatosensory cortex of monkeys with a longstanding loss of all afferents from a forelimb. One mechanism for the extensive reactivation appears to be the growth of new connections in the brain stem.