As education policy in the U.S. focuses increasingly on the quality of classroom instruction, there is a growing need to identify valid constructs and develop reliable tools that measure student opportunities to learn academic knowledge and skills. The purpose of this study is to examine the relative contributions of two different classroom observation instruments in an evaluation of classroom instruction in a comprehensive reading intervention program designed to support struggling readers. This study was conducted in 25 middle schools in six school districts in the Pacific Northwest. The intervention includes three components: (a) Reading Intervention, (b) School Engagement Intervention, and (c) Data Based Decision Making. Initial findings from this study indicate that high quality instruction matters above and beyond the quantity of instruction students receive. Overall, these findings provide initial evidence for the types of observational tools that can be used to distinguish among the diversity of classroom inputs and how such inputs impact student learning. However, these measures may be limited in their ability to identify quality of instruction within a particular content area (e.g., reading comprehension). Future research is discussed in terms of developing new observational tools to identify specific instruction within the content area of reading comprehension and its impact on student learning. Tables are appended.