The ability to read extended texts for long periods of time is a hallmark of fluent reading. No other set of reading activities or reading practice can substitute for reading a longer text with reasonable comfort and without needing to stop constantly, and without feeling fatigued or overwhelmed. It actually is an extraordinarily difficult feat to accomplish for a nonfluent reader, and it usually requires that a reader know 98–99 percent of the words in a text (three to six unknown words on a 300-word page). It requires some level of fluency and efficiency in processing words and sentences. It necessitates some awareness of how texts are structured. It assumes that commonly used strategies are carried out as a matter of routine. It also assumes reasonably efficient inferencing, monitoring, and evaluation skills; motivation to persist; and prior experiences of success with extended reading. In all these respects, extended reading is a unique skill and imposes unique task requirements. Because of its fluency requirement and time-constrained processing demands, it is also an ability that develops incrementally over a long period of time (involving implicit learning, Chapter 4).