This research report examines the interaction of persons and situations. It specifically identifies individual cognitive and motivational characteristics, preferences, and orientations of children which help to determine their relative benefit from different kinds of educational environments. The procedures and results of the main study are described. Fourth-grade children in 50 classrooms in Montgomery County, Maryland, were administered measures of various outcomes during 1973-74 school year. The impact of various classroom dimensions was investigated as well as the possibility that certain cognitive and motivational characteristics of individual children may interact with classroom dimensions to effect a combined influence on educational outcomes. Specific educational outcomes including attitudes, values, and self-assessments were selected and measured, and types of classrooms and children were identified. Models from Solomon's framework for "aptitude-treatment interactions" were used in the analysis. Conclusions show that children benefit from a setting which requires them to experience a mode of activity that they would otherwise avoid, thus providing them with something which they lack. Implications, data tables, and research instruments are included in the report. (Author/ND)