The neural circuitry mediating the ability to produce learned responses to social cues is unknown. Here, 'observer' rats watched 'demonstrator' rats that received footshocks paired with a tone; with social learning, observers learned to freeze in response to the tone. Chemogenetic inhibition of lateral amygdala (LA) neurons projecting to the medial amygdala (MeA) reduced social learning. Rats lacking neurexin 1 (a model of autism spectrum disorder (ASD)) showed disrupted LA→MeA transmission and social learning deficits that were rescued by chemogenetic activation of the MeA. LA→MeA neurons therefore regulate social learning and may be disrupted in ASD.