X0303 4 2011-05-19 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 2011-05-19 4 M 0 655 61.40 A 7295 D Common Stock 2011-05-19 4 M 0 169 51.56 A 7464 D Common Stock 2011-05-19 4 S 0 824 90.00 D 6640 D Stock Option (Right to Buy) 61.40 2011-05-19 4 M 0 655 0 D 2011-05-06 2019-05-15 Common Stock 655 328 D Stock Option (Right to Buy) 51.56 2011-05-19 4 M 0 169 0 D 2011-05-06 2018-06-12 Common Stock 169 0 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 9, 2011. On May 15, 2009, the reporting person was granted an option to purchase 983 shares of common stock. The option vests in increments based on AS&E's satisfaction of certain performance criteria. The performance criteria was met for two thirds of the goals, resulting in vesting of the option as to 655 shares. On June 12, 2008, the reporting person was granted an option to purchase 507 shares of common stock. The option vests in increments based on AS&E's satisfaction of certain performance criteria. The performance criteria was met for the goals, resulting in vesting of the option as to the remaining 169 shares. M. Colette Cooke, attorney-in-fact 2011-05-23