Altered microRNA profiles have been implicated in human brain disorders. However, the functional contribution of individual microRNAs to neuronal development and function is largely unknown. Here, we report biological functions for miR-19 in adult neurogenesis. We determined that miR-19 is enriched in neural progenitor cells (NPCs) and downregulated during neuronal development in the adult hippocampus. By manipulating miR-19 in NPCs for gain- and loss-of-function studies, we discovered that miR-19 regulates cell migration by directly targeting Rapgef2. Concordantly, dysregulation of miR-19 in NPCs alters the positioning of newborn neurons in the adult brain. Furthermore, we found abnormal expression of miR-19 in human NPCs generated from schizophrenic patient-derived induced pluripotent stem cells (iPSCs) that have been described as displaying aberrant migration. Our study demonstrates the significance of posttranscriptional gene regulation by miR-19 in preventing the irregular migration of adult-born neurons that may contribute to the etiology of schizophrenia. •miR-19 is highly expressed in adult NPCs and decreases during neuronal development•miR-19 governs migration of newborn neurons in the adult brain•Rapgef2 is a direct target of miR-19, and it controls migration of adult-born neurons•miR-19 is dysregulated in human NPCs derived from iPSCs of schizophrenic patients Proper neuronal migration is critical for brain development and function. Han et al. found that miR-19 controls migration of adult-born neurons by suppressing Rapgef2, and that miR-19 expression is dysregulated in a subset of schizophrenic patient-derived NPCs.