From 1979, Wark was selected to play for his country, usually as a defender, eventually winning 29 caps for Scotland and scoring seven goals. Jock Stein was the Scotland manager who gave him his debut, in a game held on 19 May 1979, a British Home Championship match against Wales at Ninian Park; Scotland lost 3–0. Wark scored his first international goal a week later on 26 May, again in a British Home Championship game, this time against England at Wembley. Wark's opening effort was not enough, as Scotland were defeated 3–1. A week later Wark played for Scotland in a friendly against Argentina at Hampden Park. However, the game is best remembered for the performance of Diego Maradona who scored his first international goal and whose performance led Argentina to a comfortable 3–1 win over the Scots.