Basal body temperature (BBT) readings are handicapped as fertility predictors by exogenous influences on women's temperatures, many of which could be adjusted for by the presence of a non-cycling control. We, a married, cohabiting couple, tracked our BBTs for two months. We found substantial temperature covariability. When there were difficult-to-explain changes in the female partner's temperature, similar changes in the male partner's temperature suggested that these fluctuations were not attributable to ovulation. Additionally, a clear mid-cycle widening of our temperature gap suggested that ovulation had occurred. This is a limited trial of a new method. However, the potential for substantially improving the accuracy and usefulness of a globally utilized method, coupled with its inexpensiveness, ease, and painlessness, call for a larger study.