© 2008 by Taylor & Francis Group, LLC. With ever better versions of the human genome map and other genetic technologies available, greater opportunities to study causative genetic factors for complex diseases and traits such as obesity and obesity-related phenotypes continue to emerge. Researchers have and continue to devote substantial effort in an attempt to isolate genetic markers associated with obesity. Such investigators have many opportunities to advance obesity research yet also face numerous methodological challenges. This chapter presents a brief overview of the ongoing research and reviews the current approaches, techniques, and challenges in genetic research of obesity and obesity-related phenotypes.