The August 1978 papal conclave, the first of the two conclaves held that year, was convoked after the death of Pope Paul VI on 6 August 1978 at Castel Gandolfo. After the cardinal electors assembled in Rome, they elected Cardinal Albino Luciani, Patriarch of Venice, as the new pope on the fourth ballot. He accepted the election and took the name of John Paul I.

It was the first conclave since the promulgation of Ingravescentem aetatem (1970), which made cardinals who had reached the age of 80 by the day the conclave began ineligible to participate in the balloting. There were 15 cardinals excluded by that rule. The number of votes cast for Luciani on the final ballot was so great that even the uniform opposition of these cardinals would not have changed the outcome.