Abstract: Neural stem and progenitor cell (NSPC) transplantation holds promise for treating neurological injuries and diseases, yet the mechanisms underlying therapeutic efficacy remain incompletely understood. This Perspective highlights emerging evidence that synaptic connectivity between transplanted cells and host circuits is a key determinant of functional recovery. Drawing on analyses in spinal cord injury, traumatic brain injury, and Parkinson’s disease (PD), we argue that factors such as donor cell identity, graft-host compatibility, and neuronal phenotype critically influence outcomes. A deeper understanding of circuit integration will be essential for optimizing NSPC-based therapies and advancing clinicaltranslation.