Seventy-five high school students participated in a study to investigate the transfer of critical thinking skills from language arts to social studies. Students were taught English by the researcher. For six weeks during the second quarter, the control group received traditional instruction, while the experimental group received instruction stressing critical thinking. Analyses of pretests and posttests indicated that treatment and sex interacted to improve critical thinking skills in treated females. Treatment interactions with race, status of the course (required or nonrequired), and type of course (literature or composition) did not affect critical thinking skills. (Author/AA)