The development of asthma and allergic disease involves not only genetic factors but environmental influences as well. Preventative measures many involve changes in breastfeeding, diet, environmental exposure, medications, and vaccination methods. Breastfeeding is recommended during the first 4-6 months of life. Probiotics should be consumed by mothers during pregnancy and breast-feeding. Solid foods should not be introduced to high-risk infants until four months of age. Consumption of dairy products should be delayed until 1 year, eggs until 2 years, and peanuts, nuts, and fish until 3 years of age. Exposure to tobacco smoke should be avoided by the expectant mother and by the child after birth. Ample evidence suggests that dust-mite avoidance should be performed. Diets rich in antioxidants and omega-3 fatty acids should be encouraged. No current recommended changes in vaccination practices have been proposed. Because allergy and asthma is a multifactorial process with both complex genetic and environmental components, it is mlikely that a single intervention will have a significant impact on their prevalence.