Building a text is a multidimensional endeavor. Writers must work simultaneously on the content of the text, its discursive organization, the structure of the sentences, and the individual words themselves. Knowledge of vocabulary is central to this endeavor. This study intends (1) to trace the development of writer's vocabulary depth, their vocabulary fluency in writing, and the features of the text they produce (productivity, lexical richness, and text structure) through elementary school and (2) to determine the contribution of the writer's performance and the text features to the quality of the text. One hundred and eighty bilingual Spanish/Catalan speakers from first, third, and sixth grade took part in the study. They participated in three researcher-created tasks; a "synonyms/antonyms task" to orally assess vocabulary depth; a "semantic orthographic fluency task" to examine their vocabulary fluency in writing; and a "text writing task" to evaluate text quality. Data was analyzed using structural equation modeling in order to examine the relationship between the target writer's performance and the text features of the written compositions, and the externally evaluated text quality. Results revealed that both writer's performance on vocabulary depth and semantic orthographic fluency and text features improved with school level. However, the capacity to establish meaning relations between words contributed more directly to the quality of texts than the speed to find words with a specific phonographic correspondence. External evaluation of text quality was more variable for younger students than for older students and was affected by school level mediated by writer performance and text features.