1978 (MCMLXXVIII) was a common year starting on Sunday.
- January 1 - the Armenian Folk Arts Museum opens
- April 14 - the Armenian constitution is confirmed by The Armenian SSR's Supreme Soviet.
- April 24 the Armenian Genocide monument in Lyon gets unveiled
- May 31 - The Azat Reservoir gets operational
- July 28 - installation of the monument in Spitak, dedicated to the 150th anniversary of the unification of Eastern Armenia and the Russian Empire.
- October 14 - On the 150th Anniversary of the integration of Eastern Armenia in the Russian Empire, Soviet Armenia gets awarded with its third Order of Lenin, and a ceremony is held in Yerevan.