My research collects and analyzes a unique household-level data set essential to the study of an important question: the economic impacts on Nicaraguan small farmers of the rapidly expanding market power of supermarket produce buyers. Though these new large-scale purchasers generally offer prices above the spot market, they commonly insist on higher levels of product conformity, quality or processing standards, as well as a higher minimum scale of transaction. In development economics, a prevailing hypothesis holds that the emergence of these new market institutions will raise rural living standards and benefit small farmers by increasing the market value of their agricultural production. Currently, however, there is little research to validate this conjecture. My analysis explores causal relationships between market participation and welfare for the first time, taking into account both the timing and extent of market participation and providing crucial evidence at the critical early stages of development. Building on existing studies by the Nicaraguan government, my project will generate proper longitudinal data matching market participation patterns over time to the evolution of household welfare indicators. These data allow me answer two related questions: First, What are the determinants of individual producer participation in supermarket marketing channels? Second, What impacts does participation have on household assets, incomes, and expenditures over time? This study addresses an issue of central importance in the changing context of world agriculture: can small-scale farmers benefit from new markets evolving amid globalization, or will these producers become casualties in this global process?