A new contraceptive technology may advance the science of family planning but may do little to affect health if potential users do not deem it an acceptable method. The authors conducted an acceptability study of a newly developed contraceptive method--personal hormone monitoring. A sample of 480 English volunteers present at the 6th month of a 13-month longitudinal study completed surveys regarding their attitudes toward a personal hormone monitor for the purpose of contraception. The authors used the participants' responses to determine (a) the extent to which the participants accepted the monitor, (b) how their ratings of acceptability changed over time, (c) the extent to which contextual variables predicted changes in acceptability over time, and (d) whether those contextual variables predicted final acceptability of the monitor. Results suggested that no single method of family planning is best for everyone and specified the people for whom personal hormone monitoring may be most suitable.