The question of how to facilitate pro-social behavior is one of the most pressing challenges facing behavioral scientists because answers to this question have far-reaching implications for a myriad causes of unhappiness. In many domains, such as vaccination, resource conservation, or blood donation, the outcome that is optimal for the group cannot be achieved unless individuals act beyond their narrow self-interest. The current research harnesses the principle of signaling to develop and test interventions that may inspire pro-social behavior by appealing to agents' desire to appear prosocial. Whereas some people may be motivated to contribute to the public good simply by altruistic concerns for others, even absent those purely altruistic motives, nearly everyone likes to be viewed by others as a prosocial person or to think of themselves as prosocial. In economic terms, this idea is captured by the concept of signaling -- engaging in a behavior that signals the type of person one is. Thus, a self-interested reason to engage in pro-social behavior is to signal (to oneself or to others) that one is a good person. Five sets of experiments in the current project test the idea that prosocial behavior can be increased if people are given the opportunity to use that behavior to signal their prosocial nature. In the proposed research the investigators test the effects of interventions designed based on signaling theory for their influence on prosocial behavior in a series of field and lab experiments. First, a field study in the context of a blood drive tests whether monetary incentives motivate blood donation more effectively when framed in a way that signals the pro-social motives of the decision maker to perform the behavior. Second, a study on framing messages to emphasize the signal value of vaccination examines whether parents of young children are more likely to receive an influenza vaccination for themselves after viewing a message presenting vaccination as a signal that one puts their children first than after seeing a message presenting vaccination as a signal that one puts self-care first, or after seeing either of two control messages. Third, in a study on peer recommendation, researchers will test whether a message advocating blood donation is more effective if it emphasizes the signal value of this behavior, and whether this signaling effect is more pronounced when the message comes in the form of a personalized recommendation from a co-worker as compared to a standard message from a blood drive. Fourth, three studies on social comparison will investigate whether feedback comparing one's performance to that of others promotes performance improvement in a pro-social task because the social comparison feedback serves as a signal, indicating what the performance says about the agent. Fifth, in a series of studies using a common pool resource game, researchers will explore the effect of a partitioning manipulation that signals the equitable amount for each agent to consume into order to achieve the group optimal outcome, and they will test whether the partition serves as a coordination signal. This research extends previous work in economics, social psychology, and decision research, and it applies signaling theory to the design of interventions to facilitate pro-social behavior. The body of research combines powerful field experiments with tightly controlled laboratory experimental designs to test the efficacy of signaling interventions by assessing actual behavior and examining the decision processes underlying these effects. The findings will simultaneously shed light on the nature of both pro-social behavior and signaling mechanisms.