Please use this link to access this publication. Abstract Clinical and preclinical findings have suggested a role of the endocannabinoid system (ECS) in the etiopathology of autism spectrum disorder (ASD). Previous mouse studies have investigated the role of ECS in several behavioral domains; however, none of them has performed an extensive assessment of social and communication behaviors, that is, the main core features of ASD. This study employed a mouse line lacking the primary endocannabinoid receptor (CB1r) and characterized ultrasonic communication and social interaction in CB1−/−, CB1+/−, and CB1+/+ males and females. Quantitative and qualitative alterations in ultrasonic vocalizations (USVs) were observed in CB1...