Airway clearance therapy (ACT) is used in a variety of settings for a variety of ailments. These guidelines were developed from a systematic review with the purpose of determining whether the use of nonpharmacologic ACT improves oxygenation, reduces length of time on the ventilator, reduces stay in the ICU, resolves atelectasis/consolidation, and/or improves respiratory mechanics, versus usual care in 3 populations. For hospitalized, adult and pediatric patients without cystic fibrosis, 1) chest physiotherapy (CPT) is not recommended for the routine treatment of uncomplicated pneumonia; 2) ACT is not recommended for routine use in patients with COPD; 3) ACT may be considered in patients with COPD with symptomatic secretion retention, guided by patient preference, toleration, and effectiveness of therapy; 4) ACT is not recommended if the patient is able to mobilize secretions with cough, but instruction in effective cough technique may be useful. For adult and pediatric patients with neuromuscular disease, respiratory muscle weakness, or impaired cough, 1) cough assist techniques should be used in patients with neuromuscular disease, particularly when peak cough flow is < 270 L/min; CPT, positive expiratory pressure, intrapulmonary percussive ventilation, and high-frequency chest wall compression cannot be recommended, due to insufficient evidence. For postoperative adult and pediatric patients, 1) incentive spirometry is not recommended for routine, prophylactic use in postoperative patients, 2) early mobility and ambulation is recommended to reduce postoperative complications and promote airway clearance, 3) ACT is not recommended for routine postoperative care. The lack of available high-level evidence related to ACT should prompt the design and completion of properly designed studies to determine the appropriate role for these therapies.