This six-chapter handbook is concerned with the proper care and maintenance of microorganisms recovered from water and wastewater samples. These microorganisms must be cultured and identified to determine not only what kinds of cells were present in the original sample, but also what concentrations they appeared in. The skills covered are basic to all aquatic microbiological analyses. Specific tests are not described since they are available elsewhere. The purpose is to provide a firm grounding in the proper and safe use of microbiological equipment and procedures, while at the same time encouraging analysts to recognize that a sense of fun can be an inherent part of their work. Major topic areas addressed in the six chapters are: (1) equipment and supplies; (2) media and reagents; (3) working with microorganisms; (4) membrane filtration; (5) quality assurance; and (6) laboratory safety. An appendix provides an introduction to the major groups of waterborne microorganisms. (JN)