Since its introduction in 2005, optogenetics1 has become a go-to tool for deciphering neural pathways and identifying the contributions of specific cell types to behaviors. Certain hardware requirements of these systems, however, have meant that optogenetic studies of the nervous system outside the brain in freely moving animals were largely infeasible. Two new studies, one in Nature Biotechnology2and another in a recent issue of Nature Methods3, have now described the development of fully implantable, wireless, miniature optogenetic devices that are compatible with applications in the brain, spinal cord and peripheral nerves (Fig. 1).