As the United States seeks ways to stretch its defense dollars, pursue the Global War on Terrorism, and meet other national-security challenges, it is highly likely that policymakers will increase their reliance on aircraft carriers, using them more often and in more situations than they have in the past, especially if the vessels have the additional capabilities to respond appropriately. The current and expected use of aircraft carriers led the United States Navy in fall 2004 to commission RAND to explore new and nontraditional ways that the United States might be able to employ aircraft carriers in pursuit of traditional and emerging military and homeland defense missions. Over six months, RAND created and convened two Concept Options Groups (COGs)-small groups of experienced military and civilian experts, defense analysts, and potential users who work together to identify promising ways to employ military might in nontraditional ways-to explore possible nontraditional roles for aircraft carriers. One COG explored and identified new ways that aircraft carriers could be used in combat operations; the second COG examined ways that the vessels could be used in noncombat, homeland security missions or to help the nation recover from terrorist attacks or natural disasters in U.S. territories. Among the combat recommendations to come from the COG insights are that abilities need to be enhanced to reconfigure carrier air wings; among noncombat recommendations are that the availability of nonready carriers to respond to unforeseen crises needs to be improved. This monograph summarizes the activities, findings, and recommendations of both carrier COGs. It should be of special interest to the Navy and to uniformed and civilian decisionmakers with responsibilities related to naval and carrier operations, maritime domain awareness, or homeland security.