Yinyang philosophy encompasses an essential understanding of the mechanism and laws of nature, cosmos, and human society in Chinese culture, and reaches to many other parts of Asia and around the world. The purpose of this article is to explore how yinyang philosophy can serve as a philosophical underpinning of mixed methods research (MMR). In particular, harmony, one of the important features in yinyang philosophy, is applied to interpret the design of mixed methods research. Guided by this philosophy, other beliefs about an integrated approach to using qualitative and quantitative methods fit in with the MMR approach. These underlying precepts are not necessarily held by researchers, and will be shown to indicate harmony and a dynamic equilibrium of yin and yang. This perspective provides a novel window for considering controversial issues that have arisen about the use of different philosophical underpinnings for MMR during its emergence over the past several decades. The implications are for a softer interpretation, for example, when selection of quantitative rules needs to harmonize with certain types of MMR, and validity of self-developed questionnaires needs to consider different levels of criteria for MMR.