The assessments designed for and analyzed in this study used a task-based language design template rooted in theories of language reflecting heteroglossic language practices and funds of knowledge learning theories, which were understood as transforming classroom teaching, learning, and assessment through continua of biliteracy lenses. Using a participatory action research model, we created assessment instruments for pre-service English teachers in Oaxaca, Mexico, integrating language practices from communities and classrooms into assessments. Participants completed two reading and writing tasks. Task 1 was intentionally designed to engage learners' English and Spanish languages resources. Task 2 was restricted to English-only. Our analyses indicated (1) that pre-service English teachers performed better on the multilingual task than the monolingual English task at a level of statistical significance and (2) that integrating multilingual resources within assessment design can allow test-takers to demonstrate more complex or high-order thinking skills in the language they are learning. We are offering some empirical evidence of an assessment approach that is consistent with the broadly supported principle of making use of all students' linguistic resources for the purpose of teaching and learning.