This study examined the impact of participation in a preschool theatre arts program using storytelling-storyacting (ST/SA) on the development of preschool students’ oral language, theatre arts, and social-emotional skills. Two hundred and nineteen children, 86% of whom were low income and 76% whose home language was a language other than English, engaged in 19 sessions of a ST/SA program offered by theatre arts teaching artists over the course of half a year in their urban, full-day preschool program. A wait-list control design where classrooms were randomly assigned to receive the ST/SA program in the fall or spring was used to evaluate program impact. Pre-post measurement of narrative features of students’ originally dictated stories (storycoding), theatre arts skills (direct observation), play with peers (teacher rating), and approaches to learning (teacher rating) were obtained, along with a screening for expressive language skill (direct assessment). Controlling for expressive language skills, age, gender, and English language status, results suggest that preschool children who participated in this ST/SA program, compared to those who did not, produced longer, more coherent, grammatically complex, detailed stories; showed greater independence in role playing and use of gestures; and increased their positive play interactions with peers. English-language learners (ELLs) who participated in this ST/SA program, compared to those who did not, also experienced unique growth in storytelling with longer, more detailed and grammatically complex stories and acting skills (greater use of gestures). Results confirmed that ST/SA can contribute to the school readiness of preschoolers who are low-income or learning English. ST/SA is an effective, authentic early learning strategy that is low-cost and can be used to support children, and especially English language learners.