A 6-year research project which investigated sex differences in beginning reading in the Los Angeles City Schools is reported. In 1962-63 approximately 550 first-grade children were taught reading in sex-segregated groups. It was found that boys grouped together did not gain significantly more than those in heterogeneous sex groups and that girls' overall achievement was significantly better than boys'. Teachers observed the following eight basic areas of differences in the learning patterns of boys and girls: personality style, activity levels, verbal facility, auditory discrimination, listening skills, attention span, goals and motivations, and interests. In 1963-64 and 1964-65, an experimental reader written to capture boys' interests was compared with the state adopted basal series as to the effects on boys' reading achievement; significant differences favored the experimental group. During 1965-67 a set of basal readers for grades 1 through 3 containing adventurous stories geared to the interests of boys was developed and tested with significant results. Materials for reading readiness and basal readers for grades 4 through 6 are currently being developed and tested. References are included. (CM)