The costs for carbon dioxide (CO{sub 2}) capture and storage (CCS) in geologic formations is estimated to be 6−75/tCOsub2.IntheabsenceofamandatetoreducegreenhousegasemissionsorsomeothersignificantincentiveforCCSdeployment,thiscosteffectivelylimitsCCStechnologydeploymenttosmallnichemarketsandstymiesthepotentialforfurthertechnologicaldevelopmentthroughlearning−by−doinguntilthesedisincentivesforthefreeventingofCOsub2areinplace.Byfar,thelargestcurrentfractionofthesecostsiscapture(includingcompressionanddehydration),commonlyestimatedat25-60/t CO{sub 2} for power plant applications followed by CO{sub 2} transport and storage, estimated at 0−15/tCOsub2.Ofthestoragecosts,onlyasmallfractionofthecostwillgotoaccurategeologicalcharacterization.Theseone−timecostsareprobablyontheorderof0.1/t CO{sub 2} or less as these costs are spread out over the many millions of tons likely to be injected into a field over many decades. Geologic assessments include information central to capacity prediction, risk estimation for the target intervals, and development facilities engineering. Since assessment costs are roughly 2 orders of magnitude smaller than capture costs, and assessment products carry other tangible societal benefits such as improved accuracy in fossil fuel and ground water reserves estimates, government or joint private/public funding of major assessment initiatives should underpin early policy choices regarding CO{sub 2} storage deployment and should serve as a point of entry for policy makers and regulators. Early assessment is also likely to improve the knowledge base upon which the first commercial CCS deployments will rest.