The concept of net assessment has long been considered an important tool for American national security strategists, and the Pentagon’s Office of Net Assessment is widely regarded as a key influence in security planning. However, despite calls by experts for the development of a similar net assessment office in the Department of Homeland Security (DHS), only a few tentative efforts have been made to use the concepts and methodologies of net assessment for the problem of ensuring American homeland security. This article argues that a homeland security net assessment is even more necessary today, since debates over the state of the nation’s security involve discussions not only about the seriousness of the threat but also the legitimacy of the intelligence and other efforts employed to combat that threat. It proposes a new model for a homeland security net assessment process that should be undertaken by DHS and suggests that such an assessment would expand the discussion of homeland security threats beyond terrorism and would encourage greater focus on civil liberties and disaster preparedness.