Milk powder to be consumed without further treatment to inactivate microorganisms was selected to illustrate the process for establishing and applying a microbiological criterion to assess the acceptability of a food lot. Example criteria (size of analytical unit, sampling plan and limits) were specified for mesophilic aerobic colony count and Enterobacteriaceae as indicators of the adequacy of Good Hygienic Practices and forSalmonellaas a food safety criterion. Performance characteristics were determined for each criterion using four values for standard deviation of the microbial counts to illustrate how sampling plan performance depends on the within-lot standard deviation, which is uncertain for any given lot and varies among lots. Methods of analysis were specified. A description of how to interpret the results and examples of actions that could be taken by food business operators and competent authorities are provided.