The PCS returned to membership in a governing parliamentary coalition in 1978, with its adherents remaining as part of the leadership group until 1992.

In 1991, with the fall of the Soviet Union, the PCS formally renounced communism and relaunched itself as the Sammarinese Democratic Progressive Party (PPDS).

The Christian Democratic deputies refused to attend session; instead, they occupied a factory in Rovereta and set up a provisional government there.

[4][5] After the failed attempt at a coup in 1957, the PCS remained an opposition party in San Marino, excluded from the government coalition.

The new non-communist government won reelection in September 1959, with the PCS's parliamentary delegation falling to 16 members, joined by 8 Socialists.

[7] At the national election held on May 29, 1988, the PCS garnered 28.7% of the votes cast, winning 18 of 60 seats on the General Council.

[10] In 1973, Gasperoni was moved into the more ceremonial role of party chairman, with Umberto Barulli (1921–1993) taking the helm as General Secretary.

[11] The official organ of the PCS was the newspaper La Scintilla, a publication which was not produced on a regular chronological basis.