On 5 February 2010, Secretary of Agriculture Vilsack announced that the USDA was revising its approach to achieving a national capability for animal disease traceability. The previous plan, called the National Animal Identification System (NAIS), first proposed in 2002, was being abandoned. In its place, the USDA proposes a new approach that will allow individual states (and tribal nations) to choose their own degree of within-state animal identification and traceability for livestock populations. Under this revised focus, states may choose to have no mandatory animal ID and traceability capability, or to rely on existing ID systems already in place to fight brucellosis, tuberculosis, and other contagious animal diseases, or to develop their own version of a more detailed birth-to-market ID system. This book provides a summary of current developments in the USDA's effort to establish a national animal traceability capacity with the intended goal of being able to rapidly identify and respond to an animal disease outbreak.