This research investigated whether symbolic understanding of pictures in low-functioning children with autism is mediated by iconicity and language. In Experiment 1, participants were taught novel words paired with unfamiliar pictures that varied in iconicity (black-and-white line drawings, greyscale photographs, colour line drawings, colour photographs). Unlike mental-age matched typically developing peers, children with autism generally mapped words onto pictures rather than depicted referents, however, they generalised labels more frequently in colour picture conditions. In Experiment 2, children with autism categorised a line drawing with its referent, rather than another picture, regardless of whether it was named. Typically developing children only viewed pictures as symbols when they were labelled. Overall, symbolic understanding of pictures in children with autism is facilitated by iconicity (particularly colour), but not language.