Do the same kinds of processes predict spontaneous acts of kindness and long-term caring behavior in relationships? Three studies examined predictors of immediate behaviors versus delayed, sustained behaviors. Positive feelings toward the relationship partner predicted pro-relational behaviors when the behaviors could be completed in an immediate and fairly short timespan, but not when the behaviors required performance after several days delay (Study 1) or when the behavior required continued self-regulation over a period of a week (Studies 2 and 3). Sustained behavior regulation was better predicted by factors related to self-regulation strength, such as trait conscientiousness, than it was by positive relationship feelings. However, when feelings were primed daily, the feelings–behavior link remained strong for sustained behaviors (Study 3). Together, these studies suggest that immediate pro-relational behaviors are more likely to be acts of the heart, whereas delayed, sustained pro-relational behaviors are more likely to be acts of will.