The diversity of experiences among bilingual children is reflected in the variability of abilities in each of their languages. This paper describes the CECER-DLL Child and Family, and Teacher Questionnaires and discusses the utility of these tools. These questionnaires were created to address the need for valid and reliable tools to document contextual characteristics and language experiences of young bilingual children in developmental and educational research. A multi-site validity study using the CECER-DLL Questionnaires demonstrates how children’s language skills are influenced by language exposure at home and at school, mothers’ and teachers’ skills in each language, mother’s generational status, and languages used during language and literacy activities at home. (author abstract)