Gave 54 male hooded Long-Evans rats a series of fear-conditioning trials followed by avoidance training and punishment extinction. During fear conditioning, 4 groups (CS-100, CS-33, CS-0, CS-SK) were exposed to contiguous buzzer-shock pairings; for the 5th group (RB), buzzer and shock were paired randomly in time; and the 6th group (NB) received only shock. During extinction, CS-100, RB, and NB received continuous buzzer punishment; CS-33, partial buzzer punishment; CS-SK, continuous shock punishment; and CS-0, no punishment. Avoidance responding was facilitated by both partial and continuous secondary punishment, as well as primary punishment. Running speed and resistance to extinction were increasing functions of secondary punishment percentage. While substantial sensitization and novelty effects occurred, these were considerably weaker than the secondary punishment effect. (PsycINFO Database Record (c) 2006 APA, all rights reserved)