Exhibit 11 Computation of Basic and Diluted Earnings Per Common Share . . . A. Schulman Inc. Computation of Basic and Diluted Earnings Per Common Share. Year ended August 31 ------------------------------------------ 2004 2003 2002 ------------ ------------ ------------ Net income $ 27,906,000 $ 15,954,000 $ 32,154,000 Dividends on preferred stock 53,000 53,000 53,000 ------------ ------------ ------------ Net income applicable to common stock $ 27,853,000 $ 15,901,000 $ 32,101,000 ------------ ------------ ------------ Number of shares on which basic earnings per share is calculated: Average outstanding during period 30,128,117 29,496,281 29,296,435 Add - Incremental shares under stock compensation plans 446,940 370,602 349,216 ------------ ------------ ------------ Number of shares on which diluted earnings per share is calculated 30,575,057 29,667,037 29,845,497 ------------ ------------ ------------ Basic earnings per share $ 0.93 $ 0.54 $ 1.10 ------------ ------------ ------------ Diluted earnings per share $ 0.91 $ 0.53 $ 1.08 ------------ ------------ ------------