The genus Clostridium includes a number of pathogenic species, but only a few are linked to food-borne infection and intoxication. The current chapter focuses on clostridia transmitted by food like Clostridium botulinum and C. perfringens. Additionally, the sulfite-reducing clostridia which are used as indicators for the presence of food poisoning clostridia are broadly discussed. Some of the methods are not limited in their specificity to clostridia but also detect other facultatively anaerobic bacteria, for which the term sulfite-reducing bacteria (SRB) is used. Although C. difficile-associated diseases have not been shown to be food-borne, the methods for isolating C. difficile are discussed because it has been found in food. The most widely used methods in the field of conventional microbiology are discussed. Furthermore, common confirmation methods linked to the selective agars are briefly included in the discussion. Moreover, conventional methods, especially the enrichment broths, play an important role in the enrichment of bacteria before PCR analyses. Therefore this use is discussed for C. botulinum.