Abstract: The invention provides methods of assaying fatty acid amide hydrolase (FAAH) activity adaptable for high through-put screening. The methods provide for separating a labeled substrate from at least one labeled hydrolysis product, the separation facilitating the quantification. The invention also provides methods of identifying a compound to be tested as an inhibitor or an activator of FAAH activity through the addition of the compound to be tested to a reaction mixture and comparison of the enzyme activity in the presence and absence of the compounds to be tested. The methods are adaptable for use in detecting altered FAAH activity in patients, for example, those at risk for in vitro fertilization failure, or at risk for, or suffering, addictions.