One of the most difficult and perplexing tenets of classical theism is the doctrine of divine simplicity. Broadly put, this is generally understood to be the thesis that God is altogether without any proper parts, composition, or metaphysical complexity whatsoever. For a good deal more than a millennium, veritable armies of philosophical theologians – Jewish, Christian and Islamic – proclaimed the truth and importance of divine simplicity. Yet in our own time, the doctrine has enjoyed no such support. Among many otherwise orthodox theists, those who do not just disregard it completely explicitly deny it. However, in a couple of recent articles, William E. Mann has attempted to expound the idea of divine simplicity anew and to defend it against a number of criticisms. He even has gone so far as to hint at reaffirming its importance, suggesting that the doctrine may have a significant amount of explanatory power and other theoretical virtue as part of an overall account of the nature of God, by either entailing or in other ways providing for much else that traditional theists have wanted to say about God. In this paper, I want to take a close look at Mann's formulation of the doctrine and at a general supporting theory he adumbrates in his attempt to render more plausible, or at least more defensible, various of its elements and implications. As Mann has made what is arguably the best attempt to defend the doctrine in recent years, I think that such an examination is important and will repay our efforts.