The microbial causes of pneumonia vary according to its origin and the immune constitution of the patient. Pneumonia is classified into community-acquired pneumonia (CAP), hospital-acquired pneumonia (HAP) and pneumonia in the immunocompromised. The guideline development process is guided by its scope - published after stakeholder consultation. This guideline does not cover all aspects of pneumonia, but focuses on areas of uncertainty or variable practice and those considered of greatest clinical importance. Best practice guidance on the diagnosis and management of CAP and HAP is offered, based on systematic analysis of clinical and economic evidence with the aim of reducing mortality and morbidity from pneumonia and maximising resources.