Different studies have demonstrated that people with dyslexia have difficulties in acquiring fluent reading and writing. These problems are also evident when they learn a second language. The aim of our study was to investigate if there is a linguistic transfer effect for writing in children with dyslexia when they face tasks in English (L2), as well as the possible influence of other linguistic skills (spelling, vocabulary and reading) in English (L2) and in Spanish (L1). Participants completed a series of tasks both in Spanish and English: a picture naming task, a word reading task, a word spelling task, and a written composition of which we analysed its quality through different variables provided by the Coh-metrix software. Our results revealed that children with dyslexia show similar or parallel performance in written composition in both languages, which could imply a language transfer effect from L1 and L2. Besides, basic language skills are related to the characteristics of written composition to a greater extent in English than in Spanish, suggesting the impact of these on the quality of written composition.