Certain heteroaryl-substituted piperidinyl and piperazinyl urea compounds are described, which are useful as FAAH inhibitors. Such compounds may be used in pharmaceutical compositions and methods for the treatment of disease states, disorders, and conditions mediated by fatty acid amide hydrolase (FAAH) activity, such as anxiety, pain, inflammation, sleep disorders, eating disorders, insulin resistance, diabetes, osteoporosis, and movement disorders (e.g., multiple sclerosis).