While not all diseases and conditions can be avoided, good health habits make a big difference in preventing disease and promoting health.
The CDC's Healthy Living pages offer information on dozens of topics aimed at specific age groups and populations.
Chronic Disease Prevention and Health Promotion Center – CDC
Chronic Disease Prevention and Health Promotion Programs – CDC
The IHS Health Promotion and Disease Prevention site highlights health issues with a particular focus on native populations.
The MedlinePlus site, from the U.S. National Library of Medicine, offers Health Topics, information on more than 975 diseases, health conditions, and wellness issues.
The NIH Health Information Page compiles consumer health information from the National Institutes of Health.
The Power of Prevention: Chronic Disease...the public health challenge of the 21st century – CDC Report