Quality assurance is a proactive operation to minimize the probability of errors in an analysis procedure. It also includes quality control, the operation by which the occurrence of errors is inspected once the analysis has been completed. Quality assurance procedures are described for individual steps in neutron activation analysis, namely, preparation of the test portion, selection of analytical protocol, calibration, instrument performance checks, irradiation, decay, measurement, spectrum analysis and interpretation, internal and external quality control, as well as for ensuring the technical competence of the personnel involved. The emphasis is on the procedures for instrumental neutron activation analysis (INAA), since it is the most widely applied method of neutron activation analysis (NAA).