After SCI, deficits of motor, sensory, and autonomic functions are commensurate with injury severity and level (Jaja et al. 2019; Failli et al. 2012). Advances in clinical care have reduced morbidities, increased survival, and improved neurological recovery after SCI (Freed et al. 1966; Stauffer 1975; Closson et al. 1991; Badhiwala et al. 2021). These advances have shifted the focus from complication management to improved life quality and independence with increasingly greater emphasis on recovery. For this review, by recovery, we specifically mean a measurable enduring improvement linked to improved spinal cord circuit function. This review does not focus on technological substitution of function using bypass technology such as a brain-machine interface, as covered in other chapters. Rather, we wish to discuss methods by which additional function can be obtained from limited residual connections.