Results from a randomized controlled trial demonstrated that a physician reminder letter combined with telephone counseling from a health educator significantly increased women's use of both mammograms and Pap tests in a low-income population in a managed care setting. This article presents results from a process evaluation and cost analysis of the intervention. An average of 35 minutes was spent preparing each of 304 intervention letters for mailing, including the time needed to secure signatures from 110 physicians. The results of an economic analysis suggested that this intervention cost $11.44 per recipient and $28.93 per screening test received above expected. However, intervention costs can be reduced significantly if one physician signs all letters (rather than each woman's own primary care physician) and if the health educator labor costs are diminished (e.g., by using student interns). Overall, the women under study reported that they are comfortable with both mailed and telephone reminders when they are post due for a clinical preventive service.