The Food and Drug Admin. (FDA) has approved for adult use many drugs that have been tested for adults but not for children. Yet clinicians often prescribe adult-approved drugs for children, a practice known as off-label prescribing, (1) because most drugs have not been tested in children, and (2) because clinicians presume that the safety and effectiveness demonstrated with adults generally means that the drugs are also safe and effective for children. However, research shows that this is not always true. Children may need higher or lower doses than adults, may experience effects on their growth and development, and may not respond to drugs approved for adults. Contents of this report: Understanding Drug Effects in Children; Why Manufacturers Have Not Tested Most Drugs in Children; Laws to Encourage Pediatric Drug Research; Issues for Reauthorization of These Laws; Concluding Comments. Tables. This is a print on demand report.