Mass gatherings of people at religious pilgrimages and sporting events are linked to numerous health hazards, including the transmission of infectious diseases, physical injuries, and an impact on local and global health systems and services. As with other forms of disaster, mass gathering-related disasters are the product of the management of different hazards, levels of exposure, and vulnerability of the population and environment, and require comprehensive risk management that looks beyond single hazards and response. Incorporating an all-hazard, prevention-driven, evidence-based approach that is multisectoral and multidisciplinary is strongly advocated by the Sendai Framework for Disaster Risk Reduction 2015-2030. This paper reviews some of the broader impacts of mass gatherings, the opportunity for concerted action across policy sectors and scientific disciplines offered by the year 2015 (including through the Sendai Framework), and the elements of a 21(st) century approach to mass gatherings.