This article shares findings from the implementation of an ongoing National Professional Development (NPD) project that advances second language literacy and biliteracy in secondary content areas. The project is part of a research-practice partnership between a large public university and two school districts in south Texas that engages in-service secondary school teachers seeking additional certification in English as a Second Language or Bilingual Education. Project activities adapt linguistically responsive theoretical and research perspectives to impact secondary teachers' knowledge, dispositions/beliefs, and practices. Analysis examines how secondary in-service content-area teachers reflect, narrate, and enact their professional identities as linguistically responsive teachers of emergent bilinguals (EBs) through professional learning activities. Findings describe how participants negotiated their identities as teachers of linguistically responsive instruction for EBs, as demonstrated through their engagement of reflective practices, digital language stories, and enactments of sociocultural pedagogical practices.