Purpose: Morphology, which is a bridge between phonology and orthography, plays an important role in the development of word-specific spellings. This study, which employed longitudinal sampling of typically developing students in Grades 3, 4, and 5, explored how the misspellings of words with derivational suffixes shed light on the interplay of phonological, orthographic, and morphological (POM) linguistic features as students learn to integrate POM features appropriately to generate correct spellings. Method: Sixty typically developing Grade 3 students were tested using the Spelling subtest from the Wechsler Individual Achievement Test--Second Edition (Wechsler, 2001) and were divided into superior, average, and poor spellers. Students' spelling skill was then assessed using the Wechsler Individual Achievement Test--Second Edition annually for another 2 years. Misspelled derivations from these three testing sessions were analyzed for linguistic feature errors and error complexity/severity. Differences in the integration of POM features across spelling ability levels at Grades 3-5 were analyzed with Kruskal-Wallis analyses of variance. Results: Longitudinal results demonstrated POM integration for the development of word-specific spellings involving derivational morphology was in its initial stages over Grades 3-5 and was influenced by spelling ability level. Information from a qualitative analysis revealed considerable variability in how students applied their POM knowledge to spell complex derivations. Conclusions: Word-specific spellings draw on multiple linguistic codes--P, O, and M--and their interconnections. It involves more than an understanding of orthographic rules. Rather, accurate spelling develops through an increased understanding of the phoneme-grapheme relationships as facilitated by the identification of word parts (base + or - affixes) in written language. Educational and clinical implications are discussed.