From 1970 to 1999, almost 700,000 families were settled through land reform programs in Brazil. However, lot turnover contributed to re-concentration of land and to the limited success of these programs. This dissertation explores land-use decision-making in an aging land reform settlement in the Amazon. It focuses on how farmers respond to limited access to the information and to opportunities that are typical of the frontier context. I analyze the interactions among variables affecting families, communities and the agrarian structure of the settlement, and changes in land-use and cover (LUCC) resulting from these interactions. The study site is a government sponsored colonization project (P.C. Humaitá) in the State of Acre, Brazil. Variables affecting land-use choices were analyzed and studied through a micro-level approach using remote sensing linked to social sciences’ techniques. A property grid (n=739) overlaid to satellite images (1981-2003) was used to analyze LUCC during this period. It was found that differences among social groups, access to urban centers, and use of agricultural credit contributed to explain LUCC along settlement’s lifetime. The Von Thünen approach showed that lot consolidation into larger properties was found to correlate with accessibility to urban centers, but not with deforestation. The dynamic of demographic land distribution is complex, and includes, among others, continuous arrival and departure of settlers, intergenerational changes, fragmentation and a move from larger to smaller lots and to local villages, occupational change from producer to off-farm labor, and connectivity between urban and rural families. It was also found that diversification of livelihood strategies through time comprises an important adaptive mechanism to the uncertain conditions that are present on frontier settlements, and that social learning processes help farmers deal with uncertainty and to take advantage of economic opportunities. The high lot turnover rates and increasing in Gini indexes observed in Humaitá (225%) follows similar trends observed in other Amazonian sites, such as 270% in Altamira. It results from an inappropriate model of land reform, incapable of providing minimum conditions to incoming settler families to remain on their lots. In this sense, one might ask whether lot turnover and land concentration indicate a vicious cycle of uneven land distribution in Brazil? To what extent does history repeat itself? The skewed level of support received by settled farmers and the re-concentration trends shown in this dissertation are in line with earlier studies, hence pointing to such vicious cycle. The environmental costs are substantial: forest conversion of some 63.8 million ha to agropastoral use, and depletion of biodiversity, nutrients, and hydrological resources. According to Abramovay, land reform would be more socially effective in Brazil if it had occurred before the urbanization boom of the 1960s and 1970s (which it could have helped to smooth out). Nevertheless, it still has a potential to reduce rural poverty, if more consistent regional planning and infrastructural provisioning is implemented. An alternative mechanism of financing and executing land reform programs is also needed, including: (1) selection of areas designated for land reform based on criteria of environmental and economic sustainability of future settlements, in which focus is placed on areas served by all-weather roads and close to markets, and on achieving consistency between environmental legislation by the Environmental Protection Agency of Brazil (IBAMA) and INCRA, thus avoiding the regularization of settlements on irregularly occupied forested areas; (2) public-private partnerships with more accurate studies on the capability to provide infrastructure investments and delivery of public services; (3) incorporation of representatives of the civic society around community-based programs in all phases of implementation; for example, use of a polycentric governance model based on multiple centers of decision making, formally independent of each other but under a structure of ordered relationships and rules, and with consumers as co-producers of public services; (4) diversified provision of technical assistance and agricultural credit support (also from the private sector) oriented toward the engagement of beneficiaries in agricultural markets; (5) fiscal incentives to cooperatives to establish processing plants and transformation industries of agricultural products; and (6) implementation of a land tax system based in social and environmental indicators, creating incentives for landowners to engage in sustainable projects. Further research on the outcomes of recent experiences in land reform, including multi-agency networks, negotiated land reform programs, and community-based approaches are needed.A challenge of conservation in the Amazon is to maintain forest cover outside parks. The challenge of land reform is to promote land redistribution that is compatible with economic sustainability, market integration, and long-term conservation of natural resources. There have been enough experiences in the Amazon to inform innovative governance approaches and promotion of rural development. Despite disagreements and problems, land redistribution and regularization is an historical need in Brazil and in the Amazon, and should continue to receive attention as a policy priority for the region