This paper undertakes a review of the literature on writing cognition, writing instruction, and writing assessment with the goal of developing a framework and competency model for a new approach to writing assessment. The model developed is part of the Cognitively Based Assessments of, for, and as Learning (CBAL) initiative, an ongoing research project at ETS intended to develop a new form of kindergarten through Grade 12 (K-12) assessment that is based on modern cognitive understandings; built around integrated, foundational, constructed-response tasks that are equally useful for assessment and for instruction; and structured to allow multiple measurements over the course of the school year. The model that emerges from a review of the literature on writing places a strong emphasis on writing as an integrated, socially situated skill that cannot be assessed properly without taking into account the fact that most writing tasks involve management of a complex array of skills over the course of a writing project, including language and literacy skills, document-creation and document-management skills, and critical-thinking skills. As such, the model makes strong connections with emerging conceptions of reading and literacy, suggesting an assessment approach in which writing is viewed as calling upon a broader construct than is usually tested in assessments that focus on relatively simple, on-demand writing tasks.