Neonicotinoid pesticides have been an increasing focus of the environmental community, due to their potential impacts on bee populations and other important insects. The goal of this study was to develop a lifecycle assessment (LCA) approach that could be used to quantify the environmental impacts of two common neonicotinoid pesticides, Imidacloprid and Thiamethoxam. In order to develop the LCA study, an equivalent scenario was created for each pesticide that incorporated data on the production of each pesticide, followed by transportation to a model farm site in Brazil and application with an in-furrow pesticide application system. Data sources for the materials and energy used, combined with resulting emissions to air, water, and soil, were gathered from peer-reviewed literature, government reports, life-cycle inventory databases, and other sources. The SimaPro LCA modeling platform was used to assess the impacts of each life cycle on Human Health and Ecosystem Quality, according to the Impact 2002+ method. Results indicate that important differences exist between the pesticide life cycles, with Thiamethoxam resulting in lower LCA impacts in both impact areas and most mid-point categories under study. Pesticide production impacts varied by over an order of magnitude between the Imidacloprid and Thiamethoxam, while pesticide transport was determined to be a negligible source of environmental impact in both systems. Pesticide application activity using tractors was a larger contributor to Human Health and Ecosystem Quality impacts than the ultimate effect of the pesticide emission to the environment, which should be an area of further study to confirm this finding with the pesticides in question and also to focus impact on the application systems as a potential method of reducing environmental impact, in addition to pesticide toxicity.