The writing-reading process is a total interacting system comprising four subsystems: the writer, the text, the reader, and the context. A model of the complex interactions among these four subsystems is useful to the extent that it provides a framework for established facts, and in so far as it explains phenomena and suggests hypotheses. While syntax or grammatical structure may account for arrangements among lexical items within the sentence, cohesion refers to the nonstructural resources of language needed to account for relations between sentences. When writers introduce people, objects, and places and then keep track of these, the type of cohesion principally used is reference; co-reference maintains this relationship of identity. Conjunction is the type of cohesion when writers use an explicit connective to join one section of a text to another. Lexical items drawn from a restricted domain provide lexical cohesion. Texts lacking these cohesive strategies cannot be described as "normal." Data from studies examining student perception of textual cohesion using the framework of the writing-reading systems model lend support to the general hypothesis that linguistic facility and background knowledge and experience, as well as control over textual cohesion, increase as students develop greater language ability. (JL)