In this article, the effectiveness of an intervention aimed at the development of reading motivation and reading strategies within problem-oriented learning environments is evaluated. The basic assumption underlying the intervention is that reading should occur in meaningful contexts and that reading and science should be regularly integrated. The intervention challenges pupils to investigate a self-formulated problem, read several books or texts on the topic and report the results of their study. The participants were six experimental third-grade classes and seven comparable control classes. The effects of the intervention were measured using a pretest-posttest control group design. Analyses of covariance were conducted to examine the effects as measured by a standardized Reading Comprehension Test, a Reading Comprehension Questionnaire, a Reading Strategy Test and a Reading Motivation Scale. The results showed the experimental group to outperform the control group with regard to knowledge of reading strategies (Reading Comprehension Questionnaire) and the use of such strategies (Reading Strategy Test). A significant difference in favour of the experimental group was also found for the Reading Motivation Scale. An effect on the standardized Reading Comprehension Test was not found.