Lacroix then was traded to the Chicago Black Hawks for 1971-72 before joining the WHA with the Philadelphia Blazers the following season, when he led the league with 124 points (50 goals, 74 assists). He also played for the New York Golden Blades/Jersey Knights, San Diego Mariners, Houston Aeros and New England Whalers over his seven WHA seasons.
In 1974-75, his first season with San Diego, Lacroix won his second WHA scoring title with 147 points (41 goals, 106 assists) in 78 games. He also set the professional record for assists that season; at the time, he was the only player other than Bobby Orr (102 assists for the Boston Bruins in 1970-71) who had ever reached 100 in a single season of professional hockey. The record stood until Wayne Gretzky had 109 assists for the Edmonton Oilers in 1980-81.
Lacroix is the WHA all-time leader in points (798, including 251 goals), assists (547) and games played (551).