Aversive conditioning (AC) has the potential to temporarily reduce conflicts between humans and black bears (Ursus americanus). From 2002 to 2005, I evaluated the effectiveness of projectiles with varying impact intensities, pepper spray, and chasing on approximately 150 bears in Sequoia National Park. Aversive conditioning was successful in keeping bears that were not food-conditioned from becoming food-conditioned. For the bears that were already food-conditioned, 17 of 29 bears subjected to AC abandoned unwanted behaviors, 6 required continual treatments, and 6 were killed or relocated. Success with food-conditioned bears was highest when AC was applied soon after bears obtained human food. Aversive conditioning was less successful on yearlings than adults. Rubber slugs were slightly more effective than lower impact projectiles.