This document discusses different approaches to defining the construct of reading comprehension for language assessment purposes. It begins by describing the factorial approach, which uses factor analysis of test performance to determine the separable skills involved in reading. However, this approach is limited as it focuses on the outcomes of tests rather than the actual cognitive processes involved in reading. The document then discusses the subskills approach commonly used in language pedagogy, which breaks reading down into discrete skills. However, this approach has also been criticized. The document argues that a cognitive processing approach, which examines the actual mental processes involved in real-world reading, provides a better theoretical basis for evaluating the cognitive validity of reading tests.