The significance of acute exacerbations in chronic obstructive pulmonary disease (AECOPDs) is increasingly appreciated. AECOPDs result in significant morbidity and mortality and are a significant driver of health care costs. Frequent AECOPDs are associated with poor quality of life and more rapid decline in lung function. As such, reducing their frequency or severity is a key paradigm of COPD therapy. Bronchodilators alone and in combination with inhaled corticosteroids are the current standards of care and decrease AECOPDs. Prevention of infection with chronic macrolide antibiotics or pulsed quinolones has demonstrated some promise. Vaccination against Streptococcus pneumonia and influenza is likely beneficial. Therapeutics with antiinflammatory properties, including phosphodiesterase enzyme 4 inhibitors and HMG-CoA reductase inhibitors, may reduce AECOPD frequency. Inhibiting the formation of reactive oxidant species has also been studied, with varying results. Antioxidants, including N-acetylcysteine and S-carbomethylcysteine, may reduce exacerbation frequency, but further investigation is needed. As new therapies are developed, it will be helpful to know in which patient phenotypes they are most effective and how they compare in efficacy and side-effect profiles with inhaled coricosteroids, bronchodilators, or their combination.