The Standard Days Method is a simple fertility awareness-based method of family planning with a correct-use pregnancy rate of 4.8 at 1 year and a typical-use pregnancy rate of 12. The protocol for providing the method includes guidelines for screening potential users for cycle regularity. There also are guidelines for monitoring users to determine continued method eligibility. This article explores the importance of these screening and monitoring procedures. A large existing dataset from a World Health Organization study of the Ovulation Method was used to estimate the theoretical probability of pregnancy using the Standard Days Method, with and without screening and monitoring. We used data from the efficacy study of the Standard Days Method to examine the effectiveness of current screening and monitoring procedures. Results suggest that current screening and monitoring procedures are useful in identifying women for whom the Standard Days Method is less effective. Strict adherence to these procedures is ideal, but even women who do not meet the cycle-regularity guidelines would have a relatively low probability of pregnancy.