Pesticides used to control weeds, unwanted insects, and fungi contribute to agricultural productivity and public health by preventing crop damage and controlling pests. However, pesticides may also have adverse effects. EPA's OPP reviews applications for pesticide products and registers those that it determines do not have unreasonable adverse effects on health and the environment. This book examines the extent to which EPA inspects for GLP compliance laboratories that test pesticides and the challenges EPA faces in doing so; uses the information obtained through GLP inspections in its pesticide decision-making process; and collaborates with FDA on GLP inspections.