The National Cyber Security Division (NCSD), under the US Department of Homeland Security oversees the nation-wide effort of securing and ensuring unimpeded use of the cyberspace domain. The NCSD hosts the Cyber Storm series of national cyber security exercises as an important component of the public-private cyber security partnership. This paper uses a case study approach to explore the motivations of private sector actors to contribute to the national cyber security regime by analyzing their participation in Cyber Storm II. This research tests the assumption that the private sector actors can be motivated to participate in the cooperative national security measures by empowering them to contribute to the development of the measures. It contains a literature review of cyber security challenges and current theories on self-regulation that are applicable to this partnership. The results suggest that the Department of Homeland Security has an opportunity to improve collaboration by demonstrating its ability to provide important cyber security information to the private sector.