This paper describes a professional development model aimed at improving the language skills of English Language Learners (ELLs) while they acquire grade level appropriate mathematics skills specified by the state standards. A university professor, a Mathematics/ESL Lab teacher, and a middle grades Mathematics teacher worked as a team to specify teaching and learning outcomes and redesign their lesson plans to include language-building activities using mathematics core content. While students’ test scores and journal entries provide insight into their learning of both language and mathematics, teachers’ journal entries provide insight into the transformation of their practice and their new perception of their roles as both language and mathematics teachers.