Cooperation between authorities is of great importance for effective crisis management. A new crisis management system was introduced in Sweden in 2002 to enhance the ability of public authorities to manage accidents and extraordinary events. It expects authorities to cooperate with each other both before and while dealing with such situations. An important aspect of this cooperation is the exchange of information, which is hampered when authorities are obliged to observe secrecy rules even if this limits their ability to manage accidents and extraordinary events. It may be said, therefore, that the legislation governing the exchange of information by authorities, chiefly the Public Access to Information and Secrecy Act (2009:400), is essentially at variance with the rules that require cooperation. The thesis analyses legal requirements on authorities to cooperate and exchange information when dealing with accidents and extraordinary events and how these requirements relate to secrecy rules. The study does not merely examine the legal requirements placed on authorities to cooperate and exchange information and to observe secrecy rules when dealing with accidents and extraordinary events; it also undertakes a critical analysis of the current legislation, with the aim of identifying deficiencies and ambiguities, taking as its criteria that good legislation should be clear, coherent and well-balanced. Since the thesis shows that there are deficiencies in the legislation, it also suggests improvements and alternative forms of regulation.