The Social Democratic Party (, PSD) was a political party in Mexico during the late 1970s to 1982 with a moderate leftist tendency. It was founded by , a former member of the Institutional Revolutionary Party
Advocating revolutionary nationalism and a new left stance and founded due to political reforms implemented by José López Portillo y Pacheco. The party was registered on the 14th of December 1980 which eventually became part of the 1982 elections, in which it nominated Moreno as its presidential candidate. He received 48,412 votes (0.21%) less than the 2% of the vote required to retain party registration, the party dissolved and disappeared.