A therapeutic aerosol benefits the patient only if the medication deposits in the airway. Advances in nebulizer design have made them more efficient and "user friendly," but the greatest problem with administering aerosolized medication continues to be educating patients and caregivers to use aerosol devices properly and consistently. Misuse and nonuse are the greatest impediments to effective aerosol delivery. The respiratory pattern and degree of patient cooperation also profoundly affect aerosol deposition, and those effects are greatly magnified in small children. There are many misconceptions about nebulizer use and nebulizer equipment, even in teaching hospitals, and these can have serious consequences when patients do not receive the medication they need. This review discusses how airway physiology, nebulizer technology, and patient education relate to appropriate nebulizer use. Education is critically important, but unfortunately it is often a misunderstood or neglected part of aerosol administration.