X0303 4 2011-02-02 0000005768 AMERICAN SCIENCE & ENGINEERING, INC. ASEI 0001447577 Cline Robert B AMERICAN SCIENCE AND ENGINEERING, INC. 829 MIDDLESEX TURNPIKE BILLERICA MA 01821 0 1 0 0 SVP Common Stock 2011-02-02 4 M 0 1900 46.68 A 9600 D Common Stock 2011-02-02 4 S 0 1900 90.00 D 7700 D Employee Stock Option (right to buy) 46.68 2011-02-02 4 M 0 1900 0 D 2015-02-10 Common Stock 1900 3681 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 9, 2010. On February 10, 2005, the reporting person was granted an option to purchase 5,581 shares of common stock which vested as follows: 1,581 shares on February 10, 2006, 2,000 shares on February 10, 2007 and 2,000 shares on February 10, 2008. M. Colette Cooke 2011-02-04