Asthma is a major cause of morbidity and lost productivity. Despite the tremendous burden of this disease, the scientific community is still struggling to find an effective means of prevention. The contribution of genetics to the development of atopy cannot be altered, but environmental changes as well as pharmacotherapy have been studied as modifiable risk factors. Many trials to date have been effective only for subjects with certain characteristics. This is likely because asthma is a heterogenous condition, with a variety of triggers and clinical phenotypes. Thus far, a universally effective prevention strategy has eluded us. However, if an intervention can be found to prevent asthma and the allergic march, it will greatly improve quality of life for millions of sufferers and decrease healthcare expenditures.