Mysterio made his World Championship Wrestling (WCW) debut on June 16, 1996, at The Great American Bash, challenging Dean Malenko for the WCW Cruiserweight Championship, which Malenko retained by winning. In July at Bash at the Beach, he defeated longtime rival Psicosis in a number one contender's match to earn another opportunity at the Cruiserweight title. The next night, on the July 8 episode of "WCW Monday Nitro", he defeated Malenko to win his first Cruiserweight Championship. He reigned as champion for three months, which included title defenses against the likes of Ultimate Dragon, Malenko, and Super Caló before he lost the title to Malenko at Halloween Havoc. Following his Cruiserweight Championship reign, Mysterio challenged Ultimate Dragon for the J-Crown Championship, but was unsuccessful in his title match at World War 3 in November.