Recent studies have emphasized the positive effects of early biliteracy on children’s linguistic and cognitive abilities. However, the extent to which one system affects the other is not totally understood (Finger & Brentano, in press). With that in mind, this paper presents the results of a study that aimed to compare the levels of syntactic complexity and thought organization in written production in Portuguese and in English. We predicted that both variables would correlate in the two languages, showing no negative effects of early biliteracy. Sixty children (M = 10.7) enrolled in 5th and 6th grades in a bilingual curriculum school in the metropolitan area of Porto Alegre, Rio Grande do Sul, Brazil, screened for proficiency, constituted the cohort of the study. The children’s home and community language is Portuguese, but they have been exposed to English at school for 10 hours a week for at least 5 years. Participants were asked to create a narrative based on a sequence of five images (Cambridge Assessment, 2018) one in English and one in Portuguese, in a counterbalanced order. The analysis of syntactic complexity involved the assessment of T-Units (Hunt, 1965) and thought organization was measured through the analysis of graph trajectories performed with the computational tool Speech Graphs (Mota et al., 2016, 2019). Preliminary results indicated a moderate positive correlation in the levels of syntactic complexity and in the attributes of thought connectivity in both languages, demonstrating that, as children advance in the development of more complex writing strategies in Portuguese, they progress in their written production in English to the same extent, confirming our initial predictions. These data reinforce the importance of teachers assessing students' written production in their two languages from a bilingual perspective and from a conception that the languages that make up the linguistic repertoire of the bilingual individual constitute a whole integrated system and not two independent systems that compete with each other (García, 2009).