This project is a multi-site, multi-year study designed to test the efficacy of a fully developed intervention, Collaborative Strategic Reading (CSR), with adolescent readers. In year 1, the research questions were: (1) "Does CSR improve reading comprehension for adolescent readers attending relatively low SES schools?"; and (2) "Does CSR improve reading comprehension for adolescent struggling readers attending relatively low SES schools?" This study was conducted in 6 middle schools in Texas and Colorado. Based on the current analysis, the authors conclude that there is a small, significant main effect of CSR on reading comprehension as measured by the Gates-MacGinitie assessment; but that this effect is not statistically significant for struggling readers. The authors believe that the findings from this study suggest that CSR is a feasible and effective practice that can be readily integrated into reading and language arts instruction with positive impact. They are encouraged about the potential effectiveness of this practice because the positive findings from this efficacy study resulted from treatment implementation conditions that are readily replicable. (Contains 4 tables.)