Granular materials, alone or in combination with a fluid, are ubiquitous in both nature and industry. Despite this ubiquity, the behavior of these materials offers a wide variety of unanswered questions. This has lead to sustained and strong international research spanning multiple disciplines, as the physical underpinnings continue to be revealed and new phenomena continue to be discovered. In addition, there are intriguing links between granular materials and other systems, such as glasses, colloids and foams. This fourth Gordon Conference on Granular and Granular-Fluid Flows will afford active researchers in the field an opportunity to learn about recent discoveries and to engage in discussions with other contributors to the field. Invited speakers will provide a catalyst for interactions by covering a range of topics such as dilute and dense phase flows, jamming, regime transitions, multiphase systems, avalanches instabilities, patterns, segregation/mixing, and related phenomena.