A retrospective study of 1,311 women making initial family planning visits to metropolitan-area health department clinics found that many women switch methods or discontinue use in the first year following the clinic visits. Among a subgroup of women, most of whom selected the pill as their primary method and who used the pill for at least one of the months in the study period, almost half either changed methods or used no method at some point during a follow-up period averaging eight months. This includes 13 percent of women who made two or more changes. In addition, only 42 percent said they took a pill every day, and only half of these said they always took their pill at about the same time every day. Despite such irregularities, pill users were approximately one-third as likely to get pregnant during the study period as women making an initial family planning visit to a health department clinic who did not use the pill at all.