Language, procedure, and identity are L2 teaching/learning essentials that may promote agency and stimulate synergies among knowledge, practice, and reflection (Diaz Maggioli, 2014; Duff, 2012). This meta-report presents three studies that collectively advance agency and endorse linguistic foundations as enrichment, differentiated instruction as engagement, and teacher identity as empowerment. All of these theoretical constructs are key to successful L2 teaching and acquisition. Study 1 quantitatively reports on introductory linguistics’ presence or absence in 114 master’s programs at 54 US institutions. Findings suggest that linguistics’ curricular presence is inconsistent and training for optimal impact in the L2 classroom is lacking. Given the discipline’s fundamental role in teachers’ understanding of language development, grammatical structures, and sociolinguistic contexts (Fillmore & Snow, 2000; Lucas, Villegas, & Freedson-Gonzalez, 2008), such lapses offer insufficient pedagogic tools and impair the ability to address English learners’ (ELs) needs. Study 2 profiles differentiated instruction in integrated classrooms to develop Caribbean Creole ELs’ academic writing and language skills. Findings demonstrate that scaffolding academic language and linguistic interventions within pedagogical frameworks with socially-conscious strategies benefit ELs (Matsuda, 2006; Salvatori & Donahue, 2012). This study argues differentiated instruction is essential to L2 formal register acquisition and academic success, particularly for urban STEM students. Study 3 qualitatively investigates the use of reflective practices by urban STEM teachers completing an additional ESL Endorsement. Drawing from a combined perspective of identity-in-discourse (Fairclough, 2003) and identity-in-practice (Varghese, Morgan, Johnston, & Johnson, 2005), the study explores how reflective practices embedded in a field experience/practicum impact the professional identity of in-service STEM teachers.