Where Were You When the Lights Went Out? is a 1968 American comedy film with Doris Day, directed by Hy Averback. Although it is set in New York City during the infamous Northeast blackout of 1965, in which 25 million people scattered throughout seven states in the Northeastern United States lost electricity for several hours, the screenplay by Everett Freeman and Karl Tunberg is based on the earlier 1956 French play Monsieur Masure by Claude Magnier.

This was the penultimate film of Doris Day's long career, being released two months before her final screen appearance in 1968's With Six You Get Eggroll.