Current thinking about writing considers spelling skills to be a crucial factor in its development. However, most research evidence to date comes from studies in English, which has a highly inconsistent orthography. Since the rate of spelling development is affected by degrees of orthographic consistency, cross-linguistic investigations are thus needed to determine whether English-based assumptions may be extended to more consistent orthographies. This work reports the results of a longitudinal investigation of early writing development from a cross-linguistic viewpoint. The writing development of children learning to write in English, a very inconsistent orthography, and children learning to write in Spanish, a very consistent orthography, was contrasted. Specifically, the studies included in this thesis explored the extent to which orthographic complexity moderated gains in a number of microstructural writing features, as well as whether it shaped the relationships between different levels of text construction. Finally, preschool-Year 2 predictors of writing outcomes were explored. The results showed that orthographic complexity moderates gains in wordlevel features of text writing, but, beyond the word level, both language groups showed remarkably similar performances. Spelling was found to contribute to development in the amount of text produced (text length) over a relatively short period of time. Moreover, the underlying factors driving the development of writing were common until the middle or end of Year 1. In short, orthographic consistency seems to moderate word-level writing, but has a reduced effect in text-level performance. The discussion considers the implications for models of writing development and the divide between word- and text-level writing performance.