The Party of the Social Democratic Center (Partido do Centro Democrático Social--CDS) was a Christian democratic party to the right of the political spectrum. Though not officially a religious party, the CDS was linked to mainly conservative Portuguese Catholicism and most of its officials and followers were Roman Catholic. Unlike some other Christian democratic parties, the conservative CDS did not advocate liberation theology (see Glossary). The party was founded in 1975 by Diogo Freitas do Amaral, a respected politician and a professor of administrative law.

The CDS won 15.9 percent of the vote in the 1976 elections and for a time formed a government with the PS. It increased its power when it formed an electoral coalition with the PSD in 1979 and was in power until the coalition ended in 1983. Since then the party lost much of its electoral support, gaining only a little more than 4 percent of the vote in the 1987 and 1991 parliamentary elections, and seemed consigned to lesser political significance. The strength of the PSD at the polls meant that the CDS was no longer needed to form center-right governments. A decline of the PSD seemed the only opportunity for the CDS to return to power, either with the PSD or with the PS.

Data as of January 1993