One of the most difficult problems facing researchers on writing is to define writing as a construct. The way writing is conceptualized determines how writing assignments are created and how written products are analyzed and rated. A functional approach to defining writing as a construct is presented here. It begins with the overall construct of writing activity and divides it into writing competence and writing preferences. Writing competence is defined as consisting of discourse-constructing competence and text-producing competence. Discourse-constructing competence consists of cognitive competence (idea generation and organization) and social competence (norm awareness). Text-producing competence is defined as consisting of linguistic competence and motor competence. A brief bibliography is included. (MSE)