Nolan's first Major League ballgame was at the age of only 18. A hard thrower, Nolan had a promising debut on April 15, 1967 when he struck out the side in the first inning en route to a 7-3 victory over the Houston Astros. He finished with a 14-8 record in that rookie season, was fourth in the National League in ERA (2.58) and in strikeouts (206), and was second in the Rookie of the Year voting behind Tom Seaver.