The Social Democratic Party was one of the original parties in Janda's 1950-1962 ICPP study. The party continued throughout 1950-1990 in the Harmel-Janda study of party change.

The essay on party politics in Denmark from 1950 to 1962 says:

The major governmental party during 1950 to 1962, the Social Democrats lost the government to a coalition of bourgeois parties in 1968. The party returned to office with a minority government after the 1971 elections but lost power in 1973. In 1975 and 1977 the Social Democrats again formed minority governments with support from center-right parties.

The essay on party politics in Denmark from 1963 to 2000 says:

The SD has traditionally been the strongest party in Danish politics. The party maintained strength comparative to the original ICPP period--between 35 and 43 percent of the seats--until the "earthquake" election of 1973, when its support dropped to 26 percent. The party soon recovered somewhat, but experienced depressed electoral returns of around 30 percent of the seats throughout the 1980s. The party experienced a resurgence in the 1990s, taking 39 percent of the seats in the 1990 elections and holding 36 percent in the 1994 and 1998 elections. The SD was in government through 1982--with a brief period in opposition from 1973-1975. It then spent the next 11 years in opposition, until regaining the prime minister's office in 1993.

Consult the index to variables for annual scores of the party's issue orientation, organizational complexity, centralization of power, and coherence from 1950 through 1990.