The processes of change in children's reading motivation have not been widely studied. We investigated whether situated interest for a specific book may lead to longer-term intrinsic motivation for general reading. Two schools with 120 grade 3 students filled out reading logs identifying their reasons for reading their favorite books twice. In addition, students completed general motivation and comprehension measures as a pre-assessment and as a post-assessment. Students who increased in their level of situated interest in an information book over time increased in their general reading motivation from September to December. Also, students who decreased in their level of situated extrinsic motivation for reading a narrative book decreased in general extrinsic motivation. It appeared that children's changes in situated motivation predicted their changes in general reading motivation, within an instructional context that supports engagement and motivation in reading. (Contains 5 tables and 2 figures.)