This study details the implementation and evaluation of a professional development (PD) intervention program in language and literacy for early childhood teachers using a mixed method, quasi-experimental study design. The program, Supporting Children with Language Differences (SPLD), was offered over a six-month period to 19 teachers in a federally-funded preschool program. The PD, incorporating instructional course sessions, classroom-based assignments, and onsite coaching, was designed to build teachers' capacity to promote the language and literacy development and learning of English Learner (EL) children in their classrooms. Results showed a significant positive effect of the intervention on preschoolers' oral language, receptive language, and pre-literacy skills. Moreover, the results of this study suggest that intentional inclusion of ELs in classroom activities and a sustained emphasis on the practices, strategies, and adaptations that support their inclusion may be the key to promoting ELs' language success in early childhood classrooms. (author abstract)