When bilingual children enter formal reading education, host language proficiency becomes increasingly important. This study investigated the relation between socioeconomic status (SES), maternal language use, reading input, and vocabulary in a sample of 111 six-year-old children of first- and second-generation Turkish immigrant parents in the Netherlands. Mothers reported on their language use with the child, frequency of reading by both parents, and availability of children's books in the ethnic and the host language. Children's Dutch and Turkish vocabulary were tested during a home visit. SES was related to maternal language use and to host language reading input. Reading input mediated the relation between SES and host language vocabulary and between maternal language use and host language vocabulary, whereas only maternal language use was related to ethnic language vocabulary. During transition to formal reading education, one should be aware that children from low-SES families receive less host language reading input.