Autism spectrum disorder (ASD) is a lifelong neurodevelopmental disorder, impacting social communication and in some individuals, aspects of language such as vocabulary diversity. However, we have only a limited understanding of the verbal language abilities of adults with ASD. The present longitudinal study examined conversational language and its impact on vocational independence and friendship status measured 5 years later in a sample of 84 adults with ASD. After controlling for IQ and childhood language, vocabulary diversity (a measure of structural language) predicted vocational independence and having friendships, while topic maintenance (a measure of social communication) predicted friendships. These findings highlight the importance of adult conversational language abilities for adult outcomes and quality of life.