This essay discusses Cass Sunstein’s book, Simpler: The Future of Government, in order to advance our understanding of the concepts of complex and simple law. Many writers identify complexity with uncertainty and high cost. This essay argues that complexity bears no fixed relationship to costs or benefits. It also shows that complexity’s relationship to uncertainty is so ambiguous that it is profitable to treat complexity and uncertainty as separate concepts. It develops useful separate concepts of legal and compliance complexity that will aid efforts to simplify law, like the one Sunstein claims to have embarked upon. It also argues that complexity is a hallmark of moderation, since it often arises from compromises reconciling competing interests and values. These basic points constitute important advances in the theory of complexity, which implicitly suggests something like this, but has not cleanly distinguished complex rules from costly or uncertain rules and not explicitly identified complexity with moderation. Sunstein’s book, while quite valuable in many ways, does not greatly advance discussion of how to simplify law, because he assumes that whatever happens to coincide with his political philosophy must be simpler. He is not alone in assuming a happy coincidence between his values and the simplification ideal, but this essay shows that there is little overlap between Sunstein’s endorsement of nudges and cost-benefit analysis and serious efforts to simplify the law. The theory I have articulated above leads to a keener appreciation of the need to accept some tradeoffs between simplicity and other values if we truly wish to make law “simpler.” The essay closes with some thoughts about addressing these difficult tradeoffs.