Being able to accurately spell in Standard English requires efficient coordination of multiple knowledge sources. Therefore, spelling is a word-formation problem-solving process that can be difficult to learn. The present study uses Triple Word Form Theory as a conceptual framework to analyse Standard English spelling performance levels of Australian primary school students (N = 1198) in Years 3–6. Systematic linguistic error analysis and testing using a factorial multivariate analysis of variance (MANOVA) revealed significant year-level differences in phonological, orthographic and morphological scores; however, the effects for gender and the interaction of year level and gender were non-significant. The results suggest that learning to spell may not proceed in developmental stages or phases and that explicit instruction in phonological, orthographic and morphological components of the language is needed in the middle and upper primary school years, and potentially beyond. The findings highlight a need for teachers to be informed of the specific linguistic skills that individual students bring to the classroom and to be able to identify instructional priorities among phonology, orthography and morphology.