The present invention is directed to certain Aza-Indole derivatives which are useful as modulators of Fatty Acid Amide Hydrolase (FAAH) and as FAAH imaging agents. The invention is also concerned with pharmaceutical formulations comprising these compounds as active ingredients and the use of the compounds and their formulations in the treatment of certain disorders, including osteoarthritis, rheumatoid arthritis, diabetic neuropathy, postherpetic neuralgia, skeletomuscular pain, and fibromyalgia, as well as acute pain, migraine, sleep disorder, Alzheimer Disease, and Parkinson's Disease.