Because religion and/or spirituality is integral to the lives of a majority of the world population, authors conducted 3 studies on the role of prayer in romantic relationships. Study 1 (N = 375) showed that prayer for the partner predicted lower levels of extradyadic romantic behavior over a 6-week period, over and beyond relationship satisfaction, and initial levels of extradyadic romantic behavior. In Study 2 (N = 83), they used an experimental design to show that participants assigned to pray for each day for 4 weeks engaged in lower levels of extradyadic romantic behavior during that time, compared with those who engaged in daily positive thoughts about the partner or a neutral activity. Perception of the relationship as sacred mediated the relation between experimentally manipulated prayer and later infidelity. Study 3 (N = 23) showed that objective observers rated participants who had been praying for their partner for 4 weeks as more committed to their romantic relationship than control participants. The implications of these results are then discussed. Because religion and/or spirituality is integral to the lives of a majority of the world population, they conducted 3 studies on the role of prayer in romantic relationships. Study 1 (N = 375) showed that prayer for the partner predicted lower levels of extradyadic romantic behavior over a 6-week period, over and beyond relationship satisfaction, and initial levels of extradyadic romantic behavior. In Study 2 (N = 83), they used an experimental design to show that participants assigned to pray for each day for 4 weeks engaged in lower levels of extradyadic romantic behavior during that time, compared with those who engaged in daily positive thoughts about the partner or a neutral activity. Perception of the relationship as sacred mediated the relation between experimentally manipulated prayer and later infidelity. Study 3 (N = 23) showed that objective observers rated participants who had been praying for their partner for 4 weeks as more committed to their romantic relationship than control participants. The Partner Focused Prayer Measure is used to carry this out.