The present study relates the acquisition of oral language to the development of writing in 236 children of a private school in the city of Porto Alegre, Brazil. The objective of this research was to identify non-linguistic factors involved in phonological acquisition and to describe the relation of phonological acquisition with alterations of writing. At the age of 6 years, kindergarten students were divided into 2 groups, based on the test of Phonological Evaluation of Children. In the follow-up, at 9 years of age, students were evaluated by means of Balanced Dictation and textual production. The comparison of results from case and control groups showed statistically significant difference as to the number of mistakes made in writing, pointing to the acquisition of oral language as a predictive factor for the development of spelling.