This reference surveys emerging trends, concepts, and procedures used in the characterization and control of contaminants; the sterile production of traditional drugs and biologics; the design, construction, and validation of new parenteral facilities; and the monitoring of clean environments-vividly illustrating the routes by which products, processes, and manufacturing settings become contaminated through contact with the air, water, raw materials, and the actions of personnel, as well as the current methods necessary to successfully preclude contamination.