In this developmental study, idiom understanding was examined in Australian students from Grades 5 and 8 (n = 50 per group; mean ages = 10.7 and 13.8, respectively). Twenty-four idioms with familiarity ratings ranging from high to low (as judged by Australian adolescents) were each presented in a brief story context. The students read each story and selected the best interpretation of the idiom from a set of four answer choices. Results indicated that performance on the task improved as a function of increasing grade level and that idiom familiarity was significantly correlated to idiom understanding for both groups of students. These results, which were consistent with a previous study of American students of comparable educational levels (Nippold & Taylor, 1995), provide further support for the "language experience" hypothesis of figurative language development. In replicating the previous developmental study, evidence of external validity is provided.