This manual includes laboratory procedures most often performed in wastewater laboratories and includes general wet chemistry procedures, activated sludge process control tests, bacteriological testing, and special sections about basic laboratory techniques and proper use of spectrophotometers and colorimetry. Each method (procedure) is broken down into easy-to-follow, step-by-step directions that adhere to recommendations found in Standard Methods for the Examination of Water and Wastewater and approved U.S. Environmental Protection Agency guidelines. Each method (procedure) includes a sample benchsheet. The intention of this publication is to help the operator- analyst produce analytical data that are defensible, precise, and accurate for process control and permit reporting. Special emphasis is placed on quality assurance and quality control. The introduction to each method includes a brief discussion of why the test is performed and how it can be used for process control. Most methods include typical ranges for the parameter associated with different types of treatment processes. This will help the operator- analyst determine the appropriateness of the collected samples.