Variability is important to learning; however, whether it supports or hinders language acquisition is unclear. 3D object studies suggest that children learn words better when target objects vary, however storybook studies indicate that contextual variability impairs learning. We tested a dynamic systems account in which background variability should boost learning by speeding the emergence of new behaviors. Two groups of two-year-old children saw arrays of one novel and two known objects on a screen, and heard a novel or known label. Stimuli were identical across conditions, with the exception that in the constant condition objects appeared on a white background, and in the variable condition backgrounds were colored. Only children in the variable condition showed evidence of word learning, suggesting that extraneous variability supports learning by decontextualizing representations, and indicating that adding low-level entropy to the developmental system can trigger a change in behavior.