Infectious pneumonias in the neonate can be acquired in utero, at the time of delivery, in the nursery, or at home. The pneumonia may be part of a generalized disease or the major focus of disease. Signs of disease that should prompt consideration of specific causes include respiratory distress syndrome (group B Streptococcus), empyema, lung abscesses and pneumatoceles (Staphylococcus aureus), wheezing and signs of bronchiolitis (respiratory syncytial virus), and a whoop or staccato cough (Bordetella pertussis or Chlamydia trachomatis). We review current information about the microbiology, pathogenesis, clinical signs diagnosis, and management of these and other pneumonias that affect the newborn infant. Optimal management of pneumonia in the neonate requires consideration of appropriate diagnostic techniques and presumptive therapy for the most likely cause of the disease.