Fourteen dimensions of the social climate of learning of high school classes were examined in their relationships to the size of the classes concerned. Two data samples included in the study were 149 classes participating in the 1967 evaluation of the Harvard Project Physics course and 61 classes in the Montreal Metropolitan area in a variety of subject content areas. Eight of the hypotheses supported by the Harvard data were again supported in the Montreal sample, though only two of the replications reached statistical significance. Cohesiveness and difficulty were negatively correlated with class size; that is, small classes are perceived as more difficult and more cohesive. These two statistically significant replications, as well as the six non-significant replications, were examined in their relationship to a number of paradigms for study of the effects of increasing class size on the social climate composition of the group. The study suggests a number of implications for replication work in general, as well as some specific findings relating to the climate of high school classes. Not available due to marginal legibility of original document. (Author/PR)