This study explores how preschool educators could assess dual language learners’ (DLLs) English language abilities using formative instruments in school settings. It specifically examines (1) DLLs’ receptive and expressive language proficiencies measured using the instruments and (2) educators’ perceived usefulness of them for informing instruction. Participants were 139 preschool DLLs (M = 4;9) and 37 preschool educators from four countries (Argentina, Chile, China, and US). DLLs’ families completed a questionnaire on the child’s language background, indicating the child’s home language and English abilities. Educators measured DLLs’ English proficiency using adult–child co-play activities and language observations. Afterwards, educators completed a survey regarding the usefulness of these instruments. (author abstract)