This edition of Prudent Practices in the Laboratory builds on the work provided in previous editions. Among other changes, it has two new chapters, one on Emergency Planning and one on Laboratory Security, described above, and the discussion of EHS (environment, health, and safety) management systems has been extensively revised. Chapters 2, 3, and 10 cover administrative and organizational concerns that affect the laboratory environment; Chapters 4–8 discuss practical concerns when working in a laboratory; Chapter 9 discusses laboratory facilities; and Chapter 11 provides an overview of federal regulations that affect laboratory activities. Acknowledging the stronger regulatory environment that exists today, this edition provides more references to relevant codes, standards, and regulations than the prior versions. This is not intended to imply that safety has become a matter of regulation rather than of good practice; it is a reflection of laboratory practice today and is intended to provide a resource for personnel who must remain in compliance with these regulations or face legal consequences.