This study examined joint engagement, parent labels, and language development in infants with an elevated (EL) and typical likelihood (TL) for ASD. Parent-child interactions were coded for joint engagement and parent labels at 12 and 18 months, and language skills were assessed later in toddlerhood for 12 EL infants diagnosed with ASD (EL-ASD), 17 EL infants with language delay (EL-LD), 14 EL infants with no diagnosis (EL-ND), and 12 TL infants. Infants spent substantial time in supported joint engagement and received similar rates of input from parents across outcome groups. However, parents of EL-ASD infants increased the rate of labels provided in coordinated joint engagement. While labels positively predicted language for TL infants, the opposite pattern emerged for EL-ASD infants.