Since attention to the issue of writing assessment is new, research and theory are described as still widely scattered among fields of inquiry and differing perspectives. The integration of available knowledge into a viable framework is recommended to prescribe current practice and determine future research. In a domain-referenced view of instruction and assessment, the definition of a subject, delimitation of instructional goals and efforts, sampling of criterion behaviors to describe competence are stressed. The writing skills domain is described and an approach discussed to provide the appropriate framework for integrating basic research, instruction and assessment of writing achievement. Research has begun to explore an interactive model of the writing process and its associated skills, and to describe behavioral differences to distinguish competence. To teach students a skill that transcends particular classroom instruction or task characteristics, the teaching and assessment of behaviors is suggested. The qualities of an assessment program are described. (Author/CM)