The main aim of reading is to understand what we read. To do this, the young reader needs to acquire ﬂuent and accurate word reading skills. Yet, the acquisition of good word reading alone does not guarantee adequate comprehension: a substantial proportion of young children experience signiﬁcant problems with reading comprehension despite age-appropriate word reading (Yuill & Oakhill, 1991). These poor reading comprehenders often go unnoticed because of their ﬂuent and accurate word reading. What causes their poor comprehension and what are the consequences for their literacy development? Those are the concerns of this chapter.