This is a Regional Program Review (RPR)of the World Bank's support for the MBC. The review isframed around an assessment of five Global EnvironmentFacility (GEF)-financed World Bank implemented projects inCosta Rica, Honduras, Mexico, Nicaragua and Panama that hadthe common objective of consolidating the MesoamericanBiological Corridor (MBC). It also reports on theachievements of trust fund activities, financed by the BankNetherlands Partnership Program (BNPP), that wereimplemented parallel to the GEF/World Bank projects. The MBCis a land-use planning system that spans Central America andMexico. It is designed to promote the conservation andsustainable use of the region's natural resources. Theoverall objective of the Bank's MBC projects ofconsolidating the MBC was highly relevant. Although theCentral American land bridge is very small, it is estimatedto be home to 12 percent of the world's known species.It harbors approximately 24,000 species of vascular plantsand over 500 species of mammals, many of which are endemic.The MBC derives its legitimacy from the endorsement itreceived at the Central American heads of state summit in 1997.