In the 1950s he became principal conductor of the Royal Opera, but resigned in 1960 because, as he told an interviewer in 1998, "At the Stockholm opera they wanted me to apologize for the way I led the orchestra, which I refused. I moved to America instead."

In 1963 he replaced Paul Paray as music director of the Detroit Symphony. He also conducted the Ring cycle at the Metropolitan Opera and taught at the Juilliard School after leaving Detroit in 1973.

He conducted his last concert in 2004.

Ehrling was known for his quick temper, both with musicians and audiences. According to the AP, he once had the orchestra begin before the audience had found their seats.

"I'll teach that damned audience that they should be in their seats on time when I conduct," he said afterward.