Ideologically, the party, from its foundation, adhered to Marxism–Leninism, and pursued state socialism, under which all industries in East Germany were nationalized, and a command economy was implemented.

The party's last leader, Egon Krenz, was unsuccessful in his attempt to retain the SED's hold on political governance of the GDR and was imprisoned after German reunification.

In 2007, the PDS merged with Labour and Social Justice (WASG) into The Left (Die Linke), the sixth largest party in the German Parliament following the 2021 federal election.

An early intelligence report from SVAG Propaganda Administration director Lieutenant Colonel Sergei Ivanovich Tiulpanov indicates that the former KPD and SPD members created different factions within the SED and remained mutually quite antagonistic for some time after the formation of the new party.

The report also noted considerable difficulty in convincing the masses that the SED was an authentic German political party and not merely a tool of the Soviet occupation force.

At large party meetings, members applauded speakers who talked of nationalism much more than when they spoke of solving social problems and gender equality.

By ensuring that Communists predominated on the list of candidates put forward by the National Front, the SED effectively predetermined the composition of legislative bodies in the Soviet zone, and from 1949 in East Germany.

They were also required to provide a monthly report on "Morale and Opinions" ("Stimmungen und Meinungen") concerning the people covered by their party secretarial duties.

The regional party leadership team ("SED Bezirksleitung"/ BL) was an elected body analogous to the Central Committee, membership of which was unpaid.

This meant that while the Council of Ministers was nominally the highest executive authority in the GDR, in reality it was under the permanent control of the Party Committees, a structure that ensured the "leading role" of the SED.

This status was spelled out expressly after the constitutional changes introduced in 1968, which defined East Germany as a "socialist state" led by "the working class and its Marxist–Leninist party."

The industrial sector, employing 40% of the working population, was subjected to further nationalization, which resulted in the formation of "people's enterprises" (German: Volkseigener Betrieb, VEB).

In the spring of 1971, the 8th Congress rolled back some of the programs associated with the Ulbricht era and emphasized short-term social and economic problems.

The SED used the occasion to announce its willingness to cooperate with West Germany and the Soviet Union in helping to solve a variety of international problems, particularly the future political status of Berlin.

The SED further proclaimed that greater emphasis would be devoted to the development of a "socialist national culture" in which the role of artists and writers would be increasingly important.

Most of the social and economic goals announced at the 7th Congress had been reached; however, the absence of a definitive statement on further efforts to improve the working and living conditions of the population proved to be a source of concern.

The SED sought to redress these issues by announcing, along with the Council of Ministers and the leadership of the FDGB, a specific program to raise living standards.

On the foreign policy front, the major events were various speeches delivered by representatives of West European Marxist–Leninist parties, particularly the Italian, Spanish, and French, all of which expressed in varying ways ideological differences with the Soviet Union.

At the same time, although allowing different views to be heard, the SED rejected many of these criticisms in light of its effort to maintain the special relationship with the Soviet Union emphasized by Honecker.

During the 9th Congress, the SED also responded to some of the public excitement and unrest that had emerged in the aftermath of the signing of the Helsinki Accords, the human rights documents issued at the meetings in 1975 of the Conference on Security and Cooperation in Europe.

Before the congress was convened, the SED had conducted a "People's Discussion" in order openly to air public concerns related to East Germany's responsibility in honoring the final document of the Helsinki conference.

The 10th Congress, which took place in April 1981, celebrated the status quo; the meeting unanimously re-elected Honecker to the office of general secretary, and there were no electoral surprises, as all incumbents except the ailing 76-year-old Albert Norden were returned to the Politbüro and the Secretariat.

The SED celebrated its achievements as the "most successful party on German soil", praised East Germany as a "politically stable and economically efficient socialist state", and declared its intention to maintain its present policy course.

Honecker's defense of his policy of "constructive dialogue" appeared in tune with Gorbachev's own calls for disarmament and détente in Europe.

However, the SED leadership made it unequivocally clear that its foreign policy, including relations with West Germany, would remain closely coordinated with Moscow's.

However, after a final round of talks with Gorbachev, Honecker signed a hard-line communiqué that openly attacked the policies of the West German government.

Until the 11th Party Congress, East German leaders had maintained that small and medium states had a significant role to play in international affairs.

At a special Politbüro meeting on 18 October, Honecker was voted out as general secretary and replaced by Egon Krenz, the party's number-two leader.

On 18 March 1990, the PDS was roundly defeated in the first—and as it turned out, only—free election in the GDR; the Alliance for Germany coalition, led by the Christian Democratic Union (CDU), won on a platform of speedy reunification with the West.

In 2007 the PDS merged with the western-based Labour and Social Justice – The Electoral Alternative (WASG) to create the new party The Left (Die Linke), which has resulted in a higher acceptance in western states, the party now also being represented in the parliaments of Schleswig-Holstein, Lower Saxony, Bremen, North Rhine-Westphalia, Saarland, Hesse and Hamburg.