To develop a new model of the reading process, a longitudinal study investigated the importance of the concepts of cohesion and register (fiction or nonfiction) in the assessment of text readability. Subjects, 436 8-year-olds (Cohort A), 474 10-year-olds (Cohort B), and 445 13-year-olds (Cohort C) from 23 urban and rural British schools--most of whom were average readers--participated in a silent reading comprehension project using extracts from school texts and in near normal classroom situations. Initial test results revealed that reading ability was best accommodated along a continuum rather than being related to the child's age. Findings also suggest that the large data bank of responses provided by the tests allowed analysis of chapter parts or whole chapters of books. It was also possible to map the chaining in the responses and then to compare those chain patterns with examples of similar situations in the data bank. Results suggest the possibility of advising publishers and authors on those areas of the text where readability is unclear and where learning is likely to be problematic. (Eight figures are included, and 34 references are attached.) (NKA)