Over the last five decades, Colombia hasmade substantial progress in protecting its environment.This includes restructuring its legal and regulatorylandscape, undertaking policy initiatives, and strengtheningits capacity for protecting and managing its naturalresources and environmental quality, and establishing asystem of national parks and forestry reserves that coversmore than a quarter of the country. Colombia'senvironmental management framework has focused on three mainenvironmental priorities: (a) river basin management andconservation of water resources, (b) reforestation, and (c)conservation o f biodiversity. The analysis of the cost ofenvironmental degradation conducted as part of the CountryEnvironmental Analysis (CEA), shows that the most costlyproblems associated with environmental degradation are urbanand indoor air pollution; inadequate water supply,sanitation and hygiene; natural disasters (such as floodingand landslides); and land degradation. The burden of thesecosts falls most heavily on vulnerable segments of thepopulation, especially poor children under age five. Theeffects of environmental degradation associated with theseprincipal causes are estimated to cost more than 3.7 percentof Gross Domestic Product (GDP), mainly due to increasedmortality and morbidity and decreased productivity. Toidentify alternatives aimed at abating the cost ofenvironmental degradation, this CEA examines institutionaland policy issues in the functioning of the country'senvironmental management system and suggests somecost-effective interventions.