This research measures and compares emergency services workloads and identifies factors that contribute to workload in serving the general public at mass gathering events. It derives from a collaborative project involving all emergency services that assisted at major events held in South Australia during 2003/2004. In collating workload measures for different emergency services, this research sought to ascertain if variables such as weather, crowd type and nature of an event assist in predicting the workload, across the service providers. Over 5.7 million patrons attended major events in this period. Weather arises as a primary determinant of South Australian police workload. For SA Ambulance Service and St John First Aid Service there is a broader range of determinants. There are also examples of event specific determinants. The workloads for ambulance and police correlate but there is no correlation between St John workload and the other two emergency services. The level of staffing by both ambulance and police correlated closely with the workload of each group, while for St John, no such relationship was observed. The main recommendation from this research is the need for higher quality information management across emergency services.