Picture books are a common staple of children's reading diet. The role of pictures in reading acquisition, however, remains a topic of considerable controversy. To examine the effect of pictures on second graders' (N=40) oral reading behavior and comprehension, this study used a 2 (picture condition) x 2 (genre) x 3 (reading ability) mixed ANOVA design to address three research questions: 1). What is the effect of pictures on the second graders' oral reading behavior and comprehension? 2). Does the picture effect vary across text genre? 3). Does the picture effect vary across the second graders' reading ability? Each participant read two narrative and two informational books, with or without the presence of pictures. Running Records were taken to document participants' oral reading behavior and retelling was used to measure comprehension. Statistical analyses were performed to test the picture effect and whether the effect depended on text genre or reading ability in five outcome measures, that is, oral reading errors, meaning-induced reading errors, structure-induced reading errors, visual-induced reading errors and retelling scores. Results indicate pictures facilitated reading comprehension and this facilitative effect applied to readers across different reading ability levels, not only for struggling readers. Miscue data suggest pictures might have imposed potential interference on word identification. There was no significant interaction effect between picture condition and text genre, or between picture condition and reading ability. Research data suggest that many factors associated with the reader and the text are simultaneously at work during the decoding and comprehension processes. By incorporating genre and reading ability into the research design, this study yields important insights into when, how and to whom pictures are effective or not. Pedagogically, the study suggests that pictures can be used to facilitate comprehension, especially for informational texts, yet should be used with cautions for decoding instruction. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]