The study reported in this paper examined whether a disproportionate number of boys and girls in a given grade level at various schools might have an inequitable effect on the mean achievement test scores of those schools. The student population of the Palm Beach County Schools, Florida, reflecting a cross-section of socio-economic backgrounds, had approximately 6,000 students at each grade level with the proportion of boys and girls in the system virtually identical. The data base included the third grade Stanford Achievement Test, Seventh Edition (SAT/7), Reading Comprehension, Concepts of Number, Mathematics Computaton, and Mathematics subtest scores for 1983 and 1984. The results of a 1984 preliminary study indicated grade three had the greatest number of statistically significant differences in mean Normal Curve Equivalent (NCE) reading and mathematics scores between boys and girls. Total-group and sex-dependent norms were generated for each of the four subtests and were used to develop total-group and sex-dependent district/school NCE scores. Analysis of variance, Spearman's correlation coefficient and t-tests indicated that the differences in third grade school NCE reading and mathematics means, rank orderings, and change scores were not sufficient to justify the use of sex-dependent norms. (PN)