Typically-developing (TD) children frequently refer to objects uniquely in gesture. Parents translate these gestures into words, facilitating children's acquisition of these words (Goldin-Meadow et al. in "Dev Sci" 10(6):778-785, 2007). We ask whether this pattern holds for children with autism (AU) and with Down syndrome (DS) who show delayed vocabulary development. We observed 23 children with AU, 23 with DS, and 23 TD children with their parents over a year. Children used gestures to indicate objects before labeling them and parents translated their gestures into words. Importantly, children benefited from this input, acquiring more words for the translated gestures than the not translated ones. Results highlight the role contingent parental input to child gesture plays in language development of children with developmental disorders.