Alterations in SHANK genes were repeatedly reported in autism spectrum disorder (ASD). ASD is a group of neurodevelopmental disorders diagnosed by persistent deficits in social communication/interaction across multiple contexts, with restricted/repetitive patterns of behavior. To date, diagnostic criteria for ASD are purely behaviorally defined and reliable biomarkers have still not been identified. The validity of mouse models for ASD therefore strongly relies on their behavioral phenotype. Here, we studied communication by means of isolation‐induced pup ultrasonic vocalizations (USV) in the Shank1 mouse model for ASD by comparing Shank1−/− null mutant, Shank1+/− heterozygous, and Shank1+/+ wildtype littermate controls. The first aim of the present study was to evaluate the effects of Shank1 deletions on developmental aspects of communication in order to see whether ASD‐related communication deficits are due to general impairment or delay in development. Second, we focused on social context effects on USV production. We show that Shank1−/− pups vocalized less and displayed a delay in the typical inverted U‐shaped developmental USV emission pattern with USV rates peaking on postnatal day (PND) 9, resulting in a prominent genotype difference on PND6. Moreover, testing under social conditions revealed even more prominently genotype‐dependent deficits regardless of the familiarity of the social context. As communication by definition serves a social function, introducing a social component to the typically nonsocial test environment could therefore help to reveal communication deficits in mouse models for ASD. Together, these results indicate that SHANK1 is involved in acoustic communication across species, with genetic alterations in SHANK1 resulting in social communication/interaction deficits. Autism Res 2016, 9: 696–709. © 2015 International Society for Autism Research, Wiley Periodicals, Inc.