To investigate factors which could explain the unequal participation and performance of males and females in science, the limited opportunity for females to acquire scientific literacy from their male peers in school was examined. It was assumed that males are more scientifically literate than females (even at elementary school age), that most peer learning results from same-sex as opposed to cross-sex interaction, and that cross-sex group work for science projects would increase female scientific literacy. Fourth- and fifth-grade students from 29 classrooms in California and Connecticut completed three pretests in the fall of 1980: classroom sociometric, attitude survey, and problem solving task completed once individually and once by a four person mixed-sex group. Posttests were administered the following spring. Researchers observed each classroom eight times, focusing each time on three boys and three girls randomly selected. Test results and observations were used to assess classroom organization, extent of cross-sex cooperation, willingness to participate in cross-sex interaction, and sex bias/sex stereotyping. Findings indicated that opportunities for peer learning in general and cross-sex peer learning in particular were few, students were not receptive to cross-sex grouping, and that more peer learning opportunities existed in collaborative than in non-collaborative classrooms. (DC)