The present study examined the relationship between reading (i.e., rapidity and accuracy) and writing competences (i.e., fluency, accuracy, and composition skills) of Italian children in the first and second grade. The performance of seventy-five children was longitudinally assessed over a 2-year period. Results demonstrated that reading and spelling were stable across the first two grades of primary school. Cross-lagged analyses suggested that spelling plays a pivotal role in the acquisition of formal literacy, especially within a transparent writing system like that of our Italian participants. Early progress in spelling becomes a resource for later reading acquisition. However, spelling did not correlate with the composition component of writing, suggesting the independence of these two processes. Results have implications for early childhood educators on the design and delivery of writing and reading instruction.