A study investigated the effect of research-based instructional strategies on the reading achievement of students in grades two through five. Instructional process variables were assembled into a manual used to train 24 experimental teachers. The five categories of variables were (1) classroom environment, (2) lesson introduction, (3) lesson presentation, (4) questioning, and (5) feedback. The teachers were randomly assigned, stratified by grade level, to observed or unobserved experimental groups or to a control group. The experimental treatment was designed to enhance teachers' use of reading instructional strategies associated with reading achievement. Pupils were pretested and posttested with the McGraw-Hill Prescriptive Reading Inventory. Observational data gathered on teachers' use of instructional process variables were correlated with adjusted pupil reading achievement scores to specify the strengths of associations between the two. No significant differences were found among treatment and control groups, so data were examined for differences among teachers. Significant positive correlations for "more effective" teachers were found between pupils' total reading achievement and the instructional process variables of engaging students in learning and asking direct questions. Significant negative correlations were found between achievement and the instructional variables of asking rhetorical questions and giving nonacademic commands. (HTH)