The complexity of many large-scale systems is outpacing our ability to effectively design, analyze, and manage such systems. Projects such as the F-35 Joint Strike Fighter, the Boeing Dreamliner, the Mars Science Lab, Boston’s Big Dig, and the U.S. Navy’s Independence warship have all been well over budget and behind schedule. While there may be a number of contributing factors, the enormous complexity of the designed sys-tems is certainly a culprit. Large enterprises appear to be embarking on the design of such systems without a fundamental understanding of some critical principles of complex systems. These principles are emerging in the design research community and clearly illustrate that there are some elegant and simple principles that can be used to better understand, predict, and design large-scale complex systems. In this article, a number of these principles are presented in an effort to highlight the emerging research in the sci-ence of designing complex systems. An assertion is made that simplicity and complexity can and should co-exist and if simple and elegant principles are ignored, disastrous con-sequence may await. [DOI: 10.1115/1.4023002]