Detection and enumeration of probiotic bacteria comprise major key issues in the quality assessment of probiotic dairy products. Methodologies applied depend on specific tasks as well as on diverse questions to be answered about the product. In general, the methods relate to routine and advanced laboratory techniques, whereas selective plate count methods usually form the basis for the routine assessment of viable counts of probiotic microorganisms. Some of the procedures have been standardized and therefore are well established in many laboratories. In addition, methods capable of differentiating between viable and nonviable bacterial cells have been introduced, along with a series of molecular tools, which allow a more in-depth detection and characterization of individual probiotic strains.