This article summarizes the current state of research on the prediction of infidelity and provides a foundation for advancing knowledge on this topic by offering specific recommendations for future research. The prevalence, terminological diversity, and impact of infidelity on numerous indicators of wellness is first discussed. This is followed by a discussion of the individual, relationship, and contextual factors that have received systematic attention in attempting to predict infidelity. Highlights include various demographics, the closing gender gap, cohabitation, religion, and the role of the internet in facilitating infidelity. The article concludes with 8 recommendations for more informative research to advance understanding of sexual infidelity.