This dissertation has two areas of focus: learning and developmental disorders (LDDs) and polyfluoroalkyl chemicals (PFCs). Epidemiological and exposure assessment methods are applied to each. The first paper used geographic location as a surrogate for exposure and broadly assesses the effect of the environment, both physical and social, on LDD risk in a cohort of individuals born on Cape Cod, Massachusetts. Using generalized additive models and geographic information systems, maps of the risk of LDD in the study area were produced. Results suggested that children living in certain parts of upper Cape Cod may have been more likely to have an LDD. Observed variation, although not statistically significant, may be due to local differences in the social or physical environment. The second paper evaluated the associations between exposures to four PFCs and a specific LDD, attention deficit hyperactivity disorder (AMID) using data from the National Health and Nutrition Examination Survey (NHANES) 1999-2000 and 2003-2004 for children aged 12-15 years. Results were consistent with increased odds of ADHD in children with higher serum levels of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA, C8), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS). As the sources of exposure to PFCs are not well characterized, the third paper included in this dissertation assessed the contribution of contaminated drinking water to the overall body burden of PFOA in Ohio and West Virginia communities contaminated by a fluoropolymer production facility. Standard regression approaches as well as pharmacokinetic models were used. In this population, PFOA contaminated drinking water was a significant contributor to serum levels. Regression methods and pharmacokinetic modeling produced similar estimates of the relationship. Together, these three papers make a significant contribution to the current literature on LDDs and PFCs. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]