In this article a review is given of the different types of theories that have been proposed for second language reading acquisition. Some researchers argue that reading involves a complex information processing in which a number of processes are fast and automatic, whereas others are slow and under conscious control. These authors explain the differences between monolingual and bilingual readers predominantly in terms of automatic versus controlled processes. Other authors explain the differences in reading performance in terms of ‘bottom-up’ versus ‘top-down’ processing. A third group of researchers addresses the question whether reading problems in a second language are true reading problems or language problems. Finally, a small note is given on the importance of the readers’ emotions to and perception of reading.