["TESOL Quarterly, EarlyView. ", "\nAbstract\nAddressing the educational needs of bi/multilingual students in K‐12 classrooms, this study explores teachers' engagement with multilingualism in assessment practice. Drawing on fieldwork conducted with language and mathematics teachers in Ontario, Canada, the study generates empirical insight into teachers' development and use of multilingual assessment strategies to engage students' full linguistic repertoire, cultivate multilingual awareness, and enhance students' self‐efficacy and well‐being. The study contributes to the development of fair and equitable assessment tailored to the diverse sociolinguistic landscape of Canadian schools, advocating for a paradigm shift in how language and curriculum assessments are designed and implemented.\n"]