The purpose of this contract is to operate a Clinical Center to accrue eligible patients for multi-center dietary intervention trial, the Large Bowel Polyp Dietary Intervention Trial (LBPT) being conducted by the Cancer Prevention Studies Branch, Cancer Prevention and Control. This Contractor shall participate in a study to determine whether an experimental diet (low fat, high fiber, vegetable- and fruit-enriched) will decrease the recurrence rate of large bowel adenomatous polyps.