After its election victory in 1946, it seized power in the 1948 Czechoslovak coup d'état and established a one-party state allied with the Soviet Union.

The KSČ was committed to the pursuit of communism, and after Joseph Stalin's rise to power Marxism–Leninism became formalized as the party's guiding ideology and would remain so throughout the rest of its existence.

In 1968, party leader Alexander Dubček proposed reforms that included a democratic process and initiated the Prague Spring, leading to the invasion of Czechoslovakia by the Soviet Union.

In the early postwar period the Soviet-supported Czechoslovak communists launched a sustained drive that culminated in their seizure of power in 1948.

However, KSČ held a de facto absolute monopoly on political power, and the other parties within the National Front were little more than auxiliaries.

A dispute broke out between Gottwald and the second most-powerful man in the country, party General Secretary Rudolf Slánský, over the extent to which Czechoslovakia should conform with the Soviet model.

The Soviet Union believed the process of liberalization would end state socialism in the country and on 21 August 1968, Warsaw Pact forces invaded.

An important Slovak Communist Party functionary from 1943 to 1950, Husák was arrested in 1951 and sentenced to three years, later increased to life imprisonment, for "bourgeois nationalism" during the Stalinist purges of the era.

Key members of this faction included: These hardliners opposed economic and political reforms and took a harsh stand on dissent.

Later that month, Husák, who retained the presidency after standing down as general secretary, was forced to swear in the country's first non-Communist government in 41 years.

The majority of remaining communists rejected their claim to represent the old party and continued their political career as members of KSČM.

In theory, policy matters were freely and openly discussed at congresses, conferences, membership meetings, and in the party press.

[citation needed] The supreme KSČ organ was the party congress, which normally convened every five years for a session lasting less than one week.

Between congresses, KSČ's Central Committee (CC) was responsible for directing party activities and implementing general policy decisions.

Party members holding leading positions in these bodies were responsible directly to CC for the implementation of KSČ policies.

CC, like the party congress, rarely acted as more than a rubber stamp of policy decisions made by KSČ's Presidium, except when factional infighting developed within the Presidium in 1968 and CC assumed crucial importance in resolving the dispute to oust First Secretary Novotný in favour of Dubček.

In 1987 the party also had 18 departments (agitation and propaganda; agriculture, food industry, forestry and water management; Comecon cooperation; culture; economic administration; economics; education and science; elected state organs; external economic relations; fuels and energy; industry; transport and communications; international affairs; mass media; political organisation; science and technology; social organisations and national committees; state administration; and a general department).

In most instances the party departments paralleled agencies and ministries of the government and supervised their activities to ensure conformity with KSČ norms and programmes.

In enterprises or communities where party membership was more numerous, smaller units functioned under larger city-, village- or factory-wide committees.

Highest authority of the local organisation was, theoretically, the monthly membership meeting, attendance at which was a basic duty of every member.

Since assuming power in 1948, KSČ had one of the largest per capita membership rolls in the communist world (11 percent of the entire population).

The membership roll was often alleged by party ideologues to contain a large component of inactive, opportunistic, and "counterrevolutionary" elements.

Regional and district units worked with local party organizations in setting up training programs and determining which members would be enrolled in particular courses of study.

A district or city organization provided weekly classes in the fundamentals of Marxism-Leninism, history of communism, socialist economics, and current party position on domestic and international affairs.

Members training for positions as party functionaries attended seminars at schools for Marxism–Leninism set up in local areas or at more advanced institutes for Marxism–Leninism found in Prague, Brno and Bratislava.

KSČ was often reticent with precise details about its members, and the question of how many in the party actually belonged to the revolutionary proletariat proper became a delicate one.

The proportion of workers in KSČ was at its highest (approximately 60% of total membership) after World War II but before the party took power in 1948.

Complaints ranged from members' refusal to display flags from their apartment windows on festive occasions to their failure to show up for party work brigades, attend meetings, or pay dues; a significant minority of members tended to underreport their incomes (the basis for assessing dues).

In part, this was a measure of disaffection with Czechoslovakia's thoroughgoing subservience to Soviet hegemony, a Švejkian response to the lack of political and economic autonomy.

Those expelled were often the ideologically motivated, the ones for whom developing socialism with a human face represented a significant goal; those who were simply opportunistic survived the purges more easily.