Easy-to-follow instructions for what is presented, convincingly, as the most reliable (and thoroughly documented) method of family planning available. Dr. Billings and her husband, both Melbourne physicians, developed the idea from practices of long duration in tribal groups; it is based on ""a woman's ability to identify the type of vaginal mucus produced by the cells lining the cervix prior to and during ovulation."" And World Health Organization studies--in New Zealand, Ireland, India, the Philippines, and El Salvador--have shown it to be 99 percent effective. Here, the normal menstrual cycle is explained, in conjunction with observable physical changes; and a color-coded charting system is set out for women to use in teaching themselves. Additional clear illustrations include examples from instructional materials utilized worldwide. Special attention is given, also, to the use of the method--and its advantages--in special situations: in adolescence, among women who are switching from the Pill, women who are breastfeeding, women approaching menopause (especially at risk from ""medical"" methods), and women having difficulty conceiving (who are helped to pinpoint the periods of greatest fertility). The authors explain their objections to ""the technological approach to contraception"" by pointing out the possible complications attendant upon each; they discuss the other natural methods--basal temperature, sympto-thermal--which so far have been found to be less effective. Couples with stable, long-term relationships, for whom all natural methods work best, will additionally find that the relative simplicity of this manual commends the Billings approach.