This article evaluates an intervention based on P. M. Gollwitzer's (1993) concept of implementation intentions. Women registered at a medical practice in rural England (N = 114) completed measures of the theory of planned behavior variables before a manipulation that induced one half of the sample to form implementation intentions specifying when, where, and how they would make the appointment. Subsequent attendance was determined from medical records. Findings show that the theory of planned behavior variables and previous delay behavior provided good prediction of attendance. However, despite equivalent motivation to attend, participants who formed implementation intentions were much more likely to attend for screening compared with controls (92% vs. 69%). Evidence also suggests that implementation intentions attenuated the relationship between previous delay behavior and subsequent attendance.