Only 0.2% of US women use modern methods of natural family planning, i.e., the basal body temperature and the cervical mucus methods of natural family planning (NFP). The reason that such few women use NFP methods is because they are often ineffective, they are difficult to use, there is lack of access to properly trained NFP teachers, a lack of motivation to use a behavioral method, and health professionals are reluctant to prescribe NFP methods. One way to potentially increase the use of NFP methods is to provide easy access to an effective but simplified NFP method that uses a hand held electronic hormonal fertility monitor (EHFM), an internet based charting system, and online professional support. Mutual motivation is recognized as essential for effective behavioral methods of family planning. Few studies have studied this factor in family planning efficacy.