Orthographic Knowledge as a Predictor of Writing Composition in European Portuguese: A Longitudinal Study in Grade 2

Writing development in the early grades depends critically on transcription skills, yet little is known about how components of orthographic knowledge support children's written composition in European Portuguese. This study examined whether lexical and sublexical orthographic knowledge assessed at the beginning of Grade 2 predict written composition at the end of the school year, and whether these effects are direct or mediated by word spelling. Eighty Grade 2 children completed measures of lexical orthographic knowledge (orthographic choice), sublexical orthographic knowledge (orthographic awareness), and word spelling at the beginning of the year, and a written composition task scored for lexical diversity at year's end. Path analyses with maximum likelihood estimation and bias-corrected bootstrapping showed that orthographic knowledge explained 44% of the variance in word spelling and up to 18% in written composition. Lexical orthographic knowledge was a significant direct predictor of written composition (β = 0.38, p < 0.01), whereas sublexical orthographic knowledge showed a small but significant indirect effect through spelling (β = 0.08, p < 0.05) in the full mediation model. These findings highlight the central role of orthographic knowledge, particularly its lexical component, in supporting early writing in an orthography of intermediate depth.