 Hydrological models are used to simulate the movement of water through the environment. Historically, there has been much debate over which approach to process-based hydrologic modeling is most appropriate. This paper reviews three main areas of concern, defining suitable model equations, defining adequate model parameters, and coping with limitations and computing power. Examples of modeling advancements that address these concerns are provided, as well as suggestions for future research. It is argued that the diversity of modeling approaches can be leveraged to advance our understanding of physical processes and ultimately lead to more accurate predictions of water flow. This article was authored by MP Clark, MFP Birkins, Elsamani Yego, and others.