The potential of the agricultural sector in Trinidad and Tobago has not been realized in recent decades. The more productive land resources of the country are underutilized, while many of the more fragile ecosystems are in danger. This threatens to deny the country potential income from ecotourism as well as deprive future generations of a stable land, forest, and water base. The optimal use of the country's land resources requires a stable and secure tenure system defining land rights. The Government of the Republic of Trinidad and Tobago contracted the Land Tenure Center to carry out land rationalization studies, which are intended to assist in the preparation of an action plan to deal with the problems of the land tenure system. The result was the preparation of twenty-one studies, which have been organized into two LTC research papers. This first paper explores the nature and extent of tenure insecurities in both urban and rural contexts, with a focus on agricultural land tenure problems. Several hypotheses are advanced concerning the possible constraints that legal and social insecurity of tenure pose for the future development of the country. Also explored are the environmental problems that past tenure regimes have helped generate, and what might comprise a strategy for protecting fragile ecosystems. A second paper (LTC Research Paper 116) will dig more deeply into the institutional and historical roots of the tenure insecurity problems. A final report presented to the government in August 1992 described a Land Rationalization and Development Programme, which was derived from the twenty-one studies carried out by LTC.