This study examined the extent to which land tenure and forest tenure are secured in Tanzania. It was motivated by the urgent need to solve the adverse environmental problems caused by climate change in the world today. The measures that have been devised by the international community under the UNFCCC to curb the problem within the shortest time possible include Reducing Emission from Deforestation and Forest Degradation (REDD+). This initiative was the focal point of this study with particular reference to Tanzania. he successful implementation of REDD+ requires the implementing countries to ensure that land tenure and forest tenure are secure and clear. This study draws upon experiences from the Participatory Forest Management and the ongoing REDD+ pilot projects in Tanzania, to examine the legal implications of unclear and insecure land and forest tenures in the implementation of REDD+ projects in the country. The study found that unclear and insecure land and forest tenures pose challenges when it comes to assigning carbon rights, sharing REDD+ benefits and controlling leakages.