The American Academy of Pediatrics Section on Breastfeeding recommends exclusive (meaning no water, formula or solid food) for the first six months of life.
Breastfeeding Promotion Guidelines for Childcare Centers
Breastfeeding Promotion Guidelines for Ambulatory Care Settings
Breastfeeding Promotion in Managed Care Settings
Breastfeeding Promotion in the Workplace
Breastfeeding Promotion Guidelines for Hospitals