PIP: 22 physician-providers who serve natural family planning (NFP) programs, mostly in the private sector, gathered to formulate a standard terminology for the field. The Billings and sympto-thermal methods are the 2 methods taught by this group. The sypto-thermal method helps a woman predict ovulation by detecting changes in her cervical mucus and in the cervix itself. Ovulation is confirmed by monitoring the temperature shift as well as by observing the cessation of mucus buildup, closing of the cervix, and firmness of the os. Those women using the Billings ovulation method predict fertility by the appearance of the cervical mucus, its sensation, color, and elasticity. Sperm will only survive if the cervical mucus is of the fertile type. It is also helpful to recognize mucus patterns of anovulation during breastfeeding, weaning, and premenopause. Use-effective rates which only reflect pregnancy are inadequate in evaluating NFP. A series of definitions are presented which in the future will help to analyze NFP data to accurately reflect NFP effectiveness. The terms included are: total pregnancies, planned pregnancy rate, pregnancy avoidance, method effectiveness rate, method-related pregnancies, informed choice pregnancies, teaching-related pregnancies, and unresolved pregnancies. All NPF teaching programs include instruction in basic reproductive physiology and in the recognition of the fertile phase. The cervical mucus factor is emphasized in ovulation method groups while thermal and other parameters are given equal weight in the sympto-thermal groups. It is the intent of NPF to teach couples to distinguish the fertile phase by using the fertility markers and to have them integrate this information into their sexual decision making. Success is dependent on teacher skill and the ability to inspire confidence in the method. Recognition of the mucus patterns of ovulation and anovulation are crucial in assessing infertility. All family providers under Title 10 must by law offer either NFP instruction or referrals to sites which do. A directory of non-Title 10 providers of NFP Services is available for $4.00 from the Human Life and NFP Foundation, 205 South Patrick Street, Alexandria, Virginia, 22314.