ExCELL is a year-long, online professional development program designed to help teachers of young children build language and vocabulary in the classroom. Drawing on the most current evidence about what works, ExCELL includes 6 learning modules for teachers and 4 modules for assistant teachers as well as individualized coaching for all teachers. The strategies in ExCELL can be tailored to either young children who are native speakers of English or those who are dual language learners.