We examined whether Grade 4, 6, and 8 children access the base form when reading morphologically complex words. We asked children to read words varying systematically in the frequency of the surface and base forms and in the transparency of the base form. At all grade levels, children were faster at reading derived words with high rather than low base frequencies when the words were of low surface frequency. Effects of the frequency and transparency of the base form on word reading accuracy occurred only in Grades 4 and 6. The results add to the growing body of evidence that children access the morphological structure of the words that they encounter in print.