This document provides procedures for performing testing and providing accurate, reliable, and useful results to laboratories with differing levels of expertise in anaerobe bacteriology. Preexamination requirements for specimen selection, collection, transport, timely processing, and examination procedures are discussed. Rapid and complex methods are compared for their ability to provide definitive identifications. Because the delivery of preliminary reports is vital to patient care when complex final reports are delayed, interpretations of direct smears and culture results are presented to help laboratorians confidently issue preliminary reports. Descriptions of anaerobes involved in human disease and a discussion of diagnostic methods for Clostridium difficile disease are presented. Guidelines for establishing competency testing to laboratories at their various levels of expertise and complexity are included. Because failures in good practices for preexamination, examination, and postexamination techniques can put patients at risk, a discussion of risk assessment during the design and implementation of anaerobe bacteriology protocols is included.