The Norwegian Petroleum Regulations require that operators on the Norwegian Continental Shelf coordinate and collaborate on emergency response at sea. To meet the requirements, the petroleum industry has developed a set of guidelines on how cooperation on area-based emergency response should be practiced. A study has been conducted to clarify the status, development and differences in how the operators in the various alliances execute their role in accordance with applicable regulations and guidelines. The study includes an overall mapping of all areas where formal cooperation on emergency response has been established. A total of five formal area-based emergency response alliances are identified and described. The results indicate that the area-based emergency response alliances on the Norwegian Continental Shelf function as intended. The results also indicate that the quality of the shared emergency resources has been maintained, despite the cost focus in recent years. However, there is a decline in utilization of the area-based emergency response resources in recent years.