Indirect reciprocity is deﬁned as a speciﬁc kind of behavior: An agent rewards or penalizes another agent for having behaved kindly or unkindly toward a third party. This paper analyzes the question of what drives indirect reciprocity: Does the agent reward or penalize because she (altruistically) cares for the third party? Or does she take the other agent’s behavior as a signal of how the latter would treat her if they met? In order to measure the relative importance of the altruism motive versus the signaling motive, we consider a gift-exchange game with three players: an employer pays wages to a worker and a coworker, before the worker (but not the coworker) may reciprocate by exerting eﬀort. We oﬀer a theoretical framework to analyze both motives for indirect reciprocity and run a series of lab experiments. The treatments manipulate the worker’s information on wages. We ﬁnd that, if only the coworker’s wage is observable, the worker’s eﬀort increases in the coworker’s wage. In contrast, if the worker can observe her own wage, the coworker’s wage does not aﬀect worker eﬀort at all. We interpret this as support for the signaling motive: Indirect reciprocity is rather a byproduct of direct reciprocity than an act of altruism.