The purpose of this project is to develop a new tablet-based measure in English and Spanish, Computer-Adaptive Storybook Assessment (CASA), to monitor language and literacy progress in preschoolers with disabilities or at risk for later language difficulties. Language and early literacy development are key hallmarks for later academic and social success. Studies demonstrate a relationship between language and early literacy performance during preschool across three domains (oral language, phonological awareness, and alphabet knowledge) and later reading success. There is additional evidence that many children with or at risk for disabilities lag further behind their peers, demonstrating poor reading performance in later grades. Instructionally relevant assessments are needed to support differentiated learning for preschoolers with disabilities or at risk for reading failure to help teachers apply appropriate evidence-based intervention and instruction. To meet this need, this project will develop and validate a gamified application that leads students through stories with embedded assessment items that are tailored to the child's language (English or Spanish) and are culturally relevant to assess abilities in oral language, phonological awareness, and alphabet knowledge.