This document discusses factors that affect the assessment of reading. It addresses how reading comprehension involves multiple components that depend on the format of materials and how understanding is assessed. Some key factors discussed are the language, type, and skills tested in questions. It also examines how background knowledge and text length can impact difficulty. The document explores how the reading process is internal and private, making strategies and skills difficult to isolate. However, it proposes that writing aloud and speaking protocols may help externalize some of the internal process for testing and research purposes.