This practical publication presents, in an accessible format, the main approaches to the laboratory investigation of the microbial quality of foodstuffs. As one of the largest organizations in Britain specializing in the microbiological examination of food samples, the PHLS has day-to-day experience in such work that has been drawn upon and distilled in producing this edition of the handbook. The methods described are mainly based on internationally recognised standard methods, and are therefore sound models upon which to develop procedures suitable for the wide range of foodstuffs submitted for microbiological examination and the variety of purposes for which this work is undertaken. They reflect good laboratory practice, while taking into account the need for rigorous internal and external quality assurance of all procedures.