The term lower-respiratory-tract infections (LRTIs) encompass a broad range of disease states, including acute bronchitis, pneumonia, and exacerbations of chronic lung disease. This chapter focuses on acute bronchitis, an acute inflammation of the tracheobronchial tree, is diagnosed by exclusion. Clinically it is characterized by the presence of either a productive or nonproductive cough of 4 to 6 weeks’ duration. Chronic bronchitis is part of the spectrum of chronic obstructive pulmonary disease. The chapter also focuses on pneumonia, which is an infection of the distal portion of the lungs, involving the respiratory bronchioles, alveolar ducts, sacs, and alveoli. Community-acquired pneumonia (CAP) is a major health problem in the United States and is associated with substantial morbidity and mortality and health care costs. All patients with respiratory infections should be encouraged to learn more about their disease process and become active participants in their own care.