Acquired bleeding disorders manifest in most, if not all, disease processes. The mechanistic cause underlying acquired physiologic or pathophysiologic processes may be different but the final result is a high risk of bleeding or thrombosis. Acquired hemostatic problems are encountered in pediatrics, surgery, obstetrics, and primary care, as well as in the hospitalized patient. The coagulation laboratory plays an important role in the diagnosis of these secondary coagulopathies. This chapter will focus on three frequently acquired thrombotic and bleeding manifestations secondary to a primary pathophysiologic and physiologic process: disseminated intravascular coagulation, liver disease, and newborn physiology. The laboratory tests for diagnosis and assessment will be presented, along with a discussion of the mechanism(s) and clinical presentations for these acquired coagulation disorders.