Human sexuality programs or sex education programs have been a controversial issue for many years. This study assessed the effectiveness of human sexuality programs within Catholic secondary schools. This study investigated the effects of comprehensive or non-comprehensive sexuality programs upon students positive sexual attitudes, awareness of Catholic church teachings, integration of Catholic church values, integration of current social values, and biological knowledge. Comprehensive human sexuality programs were defined as those containing three or more full semesters of classes related to sex and sexuality. Non-comprehensive human sexuality programs were defined as those containing less than two full semesters of such courses. Twelfth grade students (N=1,555) in Catholic high schools served as subjects. Analysis showed that only in the areas of positive sexual attitudes and biological knowledge were comprehensive human sexuality programs significantly different from non-comprehensive sexuality programs. Comprehensive programs within various Catholic secondary schools showed no consistency in curriculum development. Female scores were higher in Catholic church teachings and Catholic church values than males while males scored higher in social values. Students with very little or no perception of religious influence upon behavior scored higher in social values. (ABL)