Recent reports have confirmed that boys, not girls, are increasingly on the unfavorable side of the gender gap in education and developmental matters. This paper provides an analysis of trends in the gender gap among students in Catholic and public schools during the period from 1972 to 1992 for a select set of variables. Although the gender gap on test scores has received considerable attention in recent years, Catholic/public school comparisons have not been made, and very little attention has been given to variables other than test scores. Data are from three national surveys of high school students, the National Longitudinal Study (1972), the High School and Beyond Study (1980), and the National Educational Longitudinal Study (1992). The gender gap across Catholic, single sex, and coeducational schools is also considered, as well as several important demographic trends in Catholic schools. There is no evidence for a one-way gender gap favoring males beyond 1992 in either Catholic or public schools. As of that time, females possess an advantage on most central educational outcome indicators, on average. Movement towards this 1992 state of affairs can be observed in the trend results as early as 1980. At the same time, females have lost a gender gap advantage that they previously held on two other variables that are indirectly related to educational outcomes. All of this suggests that the broad nationwide efforts to bring about gender equity in schools has been effective. As a result of these trends, however, boys rather than girls are now on the short end of the gender gap in many school outcomes. Two appendixes describe the national survey data sets and list the variables studied. (Contains 8 figures, 3 tables, and 55 references.) (SLD)