The present study sought to evaluate the effects of a reading strategy instructional program on the reading competence of third-grade students. Students were instructed in fluent and strategic reading by trained research assistants in whole class settings and subsequently worked on expository text material together with peers. Their reading competence was assessed continuously: in the baseline phase prior to the intervention (4 times), while the intervention was in place (8 times), and after the end of the intervention (4 times). Additionally, reading competence in the wait list control students was assessed 8 times during the same time period. Accordingly, within- and between-group comparisons of students' test scores were conducted on the data, with both resulting in significant positive effects on the reading competence of intervention students. This research provides an example of how to strengthen the validity of quasiexperimental intervention research through the addition of design features like multiple measurement points.