Bureaucratic centralism under the direction of KSČ leadership was introduced. Dissident elements were purged from all levels of society, including the Roman Catholic Church. The ideological principles of Marxism-Leninism and socialist realism pervaded cultural and intellectual life.
The economy was committed to comprehensive central planning and the abolition of private ownership of capital.
Czechoslovakia became a satellite state of the Soviet Union; it was a founding member of the Council for Mutual Economic Assistance (Comecon) in 1949 and of the Warsaw Pact in 1955. The attainment of Soviet-style command socialism became the government's avowed policy.
Slovak autonomy was constrained; the Communist Party of Slovakia (KSS) was reunited with the KSČ (Communist Party of Czechoslovakia), but retained its own identity. Following the Soviet example, Czechoslovakia began emphasizing the rapid development of heavy industry. Although Czechoslovakia's industrial growth of 170 percent between 1948 and 1957 was impressive, it was far exceeded by that of Japan (300 percent) and the Federal Republic of Germany (almost 300 percent) and more than equaled by Austria and Greece.
Beneš refused to sign the Communist Constitution of 1948 (the Ninth-of-May Constitution) and resigned from the presidency; he was succeeded by Klement Gottwald. Gottwald died in March 1953. He was succeeded by Antonín Zápotocký as president and by Antonín Novotný as head of the KSČ.
In the 1950s, the Stalinists accused their opponents of "conspiracy against the people's democratic order" and "high treason" in order to oust them from positions of power. In all, the Communist Party tried 14 of its former leaders in November 1952 and sentenced 11 to death.
The 1960 Constitution declared the victory of socialism and proclaimed the Czechoslovak Socialist Republic (CSSR).
De-Stalinization had a late start in Czechoslovakia. In the early 1960s, the Czechoslovak economy became severely stagnant. The industrial growth rate was the lowest in Eastern Europe. As a result, in 1965, the party approved the New Economic Model, introducing free market elements into the economy. The KSČ "Theses" of December 1965 presented the party response to the call for political reform. Democratic centralism was redefined, placing a stronger emphasis on democracy. The leading role of the KSČ was reaffirmed, but limited. Slovaks pressed for federalisation.
On 5 January 1968, the KSČ Central Committee elected Alexander Dubček, a Slovak reformer, to replace Novotný as first secretary of the KSČ. On 22 March 1968, Novotný resigned from the presidency and was succeeded by General Ludvík Svoboda.