Iconic words imitate their meanings. Previous work has demonstrated that iconic words are more common in infants' early speech, and in adults' child-directed speech (e.g., Perry et al., 2015; 2018). This is consistent with the proposal that iconicity provides a benefit to word learning. Here we explored iconicity in four diverse language development datasets: a production corpus for infants and preschoolers (MacWhinney, 2000), comprehension data for school-aged children to young adults (Dale & O'Rourke, 1981), word frequency norms from educational texts for school aged children to young adults (Zeno et al., 1995), and a database of parent-reported infant word production (Frank et al., 2017). In all four analyses, we found that iconic words were more common at younger ages. We also explored how this relationship differed by syntactic class, finding only modest evidence for differences. Overall, the results suggest that, beyond infancy, iconicity is an important factor in language acquisition.