Identifying causal relations is fundamental to understanding which social and behavioral factors cause variations in obesity, which is a field of both intervention and prevention. Discussions of causation are often limited to a dichotomy of ordinary association tests versus randomized controlled trials, yet there are many other considerations and techniques available to advance causal understanding of obesity. Effectively employing techniques to produce, evaluate, and select among intervention and prevention strategies, as well as to understanding obesity's root causes, requires understanding of underlying principles to tailor approaches to specific and varying situations. Advances in behavioral obesity research require input from disciplines including statistics, economics, psychology, epidemiology, mathematics, philosophy, behavior, genetics, and more.