During the war, most of the members of the domestic resistance movement had gradually become ever more leftist in their ideology, since they were so vehemently opposed to the extreme right ideals that were ruling at the time. Czechoslovakia's first post-war government was constructed exclusively from the political parties of the leftist "National Front." Democratic life in Czechoslovakia has never fully recovered. The coal mines, heavy industry, food production, banks and private insurance companies were taken into public ownership. More than 3,000 companies, representing about two-thirds of the overall industrial capacity of the country at that time were nationalised.

In 1945, 700,000 Germans were expelled from Czechoslovakia under an agreement which was sanctioned by the Allies. In a second and more organised wave of deportations in 1946, 1.3 million Germans were deported to the American zone (in what would become West Germany) and 800,000 to the Soviet zone (in what would become East Germany). Another 200,000 Germans had fled voluntarily before the end of the war to the American zone, and around 200,000 escaped to Austria. In total, this came to around 3.2 million deportations, whether forced or voluntary over a two year period and amounted to a sizeable percentage of the overall population of the country (the current population is 10.5 millions). According to the Presidential Decrees, property which had belonged to many of these people was confiscated and put under "national supervision" and the people themselves were deprived of their Czechoslovak citizenship.

On June 5, 1947, U.S. Secretary of State George C. Marshall delivered a speech in which he offered assistance (which came to be known as the Marshall Plan) from the United States to all the countries of Europe for the reconstruction of their economies damaged during the war. The Soviet Union had already refused to participate in the plan as early as June 1946. Of the future Soviet Bloc countries, only Czechoslovakia considered taking part in the Marshall Plan. After consultations with Stalin, however, Czechoslovakia, too, refused the aid. For the next four decades, Czechoslovakia would continue to follow Soviet orders. In 1960, the Communists adopted a new constitution which officially changed the name of the country to "The Czechoslovak Socialist Republic (CSSR)" because, as a socialist society, the first step on the road to true communism had already been achieved in the country. But even this new name did not help to slow the country's rapid and alarming economic decline.

Fear diminished and political and artistic freedoms increased in Czechoslovakia in the 1960's. Changes also took place in the Central Committee of the Communist Party of Czechoslovakia. A bit like Gorbacev would do decades later in the Soviet Union, Dubcek set out to reform all aspects of life in the country. In effect, he was doing little more than giving a legal stamp of approval to the grassroots changes that were already taking place. For the first time since 1948, the government proclaimed the legitimacy of basic human rights and liberties in Czechoslovakia, and objected to the persecution of people for their political convictions.

The reforms that enabled this growing freedom were, in the words of Alexander Dubcek, an attempt to create "Socialism with a human face," and came to be known as the "Prague Spring." They were also considered to be terribly threatening by those in power in the Soviet Union as they compromised the uniformity of the Soviet bloc. Over the night of August 20-21 1968, Warsaw Pact forces (with the exception of Romania, which refused to participate) invaded Czechoslovakia, beginning a 20-year period of occupation and "normalisation."

Czechoslovak reformists tried to preserve at least some of the achievements of their reform efforts. One of these was the constitutional issue, which gave more autonomy to Slovakia. On October 28, 1968, the Czechoslovak National Assembly approved a new constitutional law on the creation of a Czechoslovak Federation. It was signed into law by President Svoboda at Bratislava Castle on October 30, and it decreed that Czechoslovakia be divided internally into two separate Czech and Slovak Republics. The federal setup took effect on January 1, 1969. But just two months later, the Federal Assembly adopted three more new constitutional laws curtailing and in fact, undermining the previous amendment meaning that the new federation existed in name only. State administration was again strictly centralised.

The easygoing leaders of the 1960's were banned (Dubcek spent the next 20 years in the Slovak forestry service) and replaced by hard-nosed hardliners. The new Communist government was one of the most repressive in all of the East Bloc - surpassed only by East Germany and Albania. The subsequent period of "normalisation" during the 1970's and about half of the 1980's, like the Counter-Reformation, was a bleak and unhappy time for the nation. The architecture of the time reflects this; most of the construction during this period was focused on building large scale "pre-fabricated housing" districts on the outskirts of cities. Evidence of this can be seen on the outskirts of Zdar nad Sazavou in a district locally known as ‘Stalingrad’.