Since 1947, shifting coalitions among the three largest parties have governed the country. The Christian Social Party (Parti Chrétien Social—PCS) is a Catholic, promonarchist movement favoring progressive labor legislation and government protection for farmers and small business. Except for the period 1974–79, the PCS has been the dominant partner in all ruling coalitions since World War I. The Socialist Party (Parti Ouvrier Socialiste Luxembourgeois—POSL) supports improvement and extension of the present system of social welfare programs. The third major group, the Democratic Party (Parti Démocratique—PD), favors social reforms and minimal government activity in the economy. Other parties have included the Luxembourg Communist Party (Parti Communiste—PC), which has its main strength with steelworkers in the industrialized south, and the Social Democratic Party (Parti Social-Démocrate Luxembourgeois— PSDL), which split from the POSL in 1971. In addition, the ecologist Green Party has representation in parliament, as does the Action Committee for Democracy and Justice (ADR), a pensioners' party. The Marxist and Reformed Communist Party, known as "The Left," secured one seat in the Chamber of Deputies in 1999.
Following the June 1999 elections, the distribution of seats in the 60-member unicameral Chamber of Deputies was: PCS, 19; POSL, 13; PD, 15; and other groups, 13. The coalition of the PCS and POSL, which had governed for 15 years, was replaced by a coalition of the PCS and PD. Jean-Claude Juncker, leader of PCS, remained as prime minister.