Marketing scholars propose that service employees play a primary role in delivering service quality. However, the question of how to motivate service employees to enhance service production has received little research attention. The authors address this gap by advocating a control mechanism first discussed in the economics literature—buyer monitoring. The authors focus on a pervasive form of buyer monitoring, voluntary tipping, and examine the effectiveness of this control mechanism as a means of improving service in two different contexts: leisure cruises and restaurant dining. Despite a substantial interdisciplinary literature reporting a weak relationship between customer perceptions of service and their tipping behavior, results show that a policy of voluntary tipping has positive effects on the motivation and behavior of service workers and on customers’ perceptions of the service those workers provide. These findings call attention to buyer monitoring as both a topic for academic research and a practical mechanism for motivating service employees. The findings also call into question trends away from tipping in service contexts such as the cruise industry and suggest that many service businesses for which tipping is not viable may benefit from alternative forms of buyer monitoring.