Although worship has a pivotal place in religious thought and practice, philosophers of religion have had remarkably little to say about it. In this paper we examine some of the many questions surrounding the notion of worship, focusing on the claim that human beings have obligations to worship God. We explore a number of attempts to ground our supposed duty to worship God, and argue that each is problematic. We conclude by examining the implications of this result, and suggest that it might be taken to provide an argument against God's existence, since theists generally regard it is a necessary truth that we ought to worship God.