This document contains two studies. The first investigates naturally-occurring aptitude-treatment interactions (ATI) with three teaching approaches--lecture-recitation, inquiry, and public issues discussion. The second study attempts to replicate these ATI in a short-term project. Teachers taught social studies to ninth-grade students according to one of the three teaching methods. Students completed aptitude measures at the beginning of each study and achievement measures at the end of each study. Results indicate that when an experimenter-constructed test was the outcome, the lecture-recitation approach was superior. However, relative effectiveness of the approaches also depends on students' ability and level of conformance. When the measure of the student performance was based on objectives of the approach, the results indicated an ATI for ability x anxiety that was partially replicated across the studies. (Author)