This article reports on two studies using "Language Muse[superscript SM]" (LM), a web-based, teacher professional development (TPD) application designed to enhance teachers' linguistic awareness and to support teachers in the development of language-based instructional scaffolding for English language learners (ELL). In Study 1, in-service teachers enrolled in certification courses learned how to use the natural language processing (NLP) component of LM to support their knowledge, awareness, practice, and application in designing instruction to ELLs. Measurement outcomes from the TPD study indicated that productive use of linguistic feedback in Language Muse led to some increases in teachers' linguistic knowledge and awareness, and in their ability to develop appropriate language-based instruction for ELLs. In Study 2, a school-based study was conducted to evaluate the feasibility of implementing LM in authentic settings. Outcomes from the study demonstrate the feasibility of implementing the Language Muse program in applied school and classroom contexts.