Preschoolers with developmental speech and/or language impairment: Efficacy of the Teaching Early Literacy and Language (TELL) curriculum

•Teaching Early Literacy and Language TELL is a tier one curriculum tested in an RCT with 91 teachers and the 289 children with developmental speech and/or language impairmen.•Curriculum-based measures developed for TELL were administered to all children at six time points across the school year.•Growth curve estimates indicated increased magnitude of growth for children who received TELL when compared to children in the BAU condition.•CBMs data indicated that children in TELL significantly outperformed their BAU counterparts in all skill areas.•A TELL effect was noted for one of the distal measures (pre-post receptive and expressive vocabulary).