This study examined the core linguistic factors affecting the writing proficiency of Grade V learners and developed, validated, implemented, and evaluated contextualized writing activities under Project WRITE. Anchored on Sociocultural Theory, Contextual Learning Theory, and Process Writing Theory, the study employed a Research and Development (R&D) design combined with a quasi-experimental pretest-posttest approach. The respondents included 72 Grade V learners from Bonga Elementary School i