The party was founded on January 1, 1965. In 1978 the party overthrew the government of Mohammed Daoud Khan (the so-called Saur Revolution). The PDPA declared the founding of the Democratic Republic of Afghanistan. Soon after the PDPA takeover, armed conflict broke out in the country. During the remainder of its governance thousands of Soviet troops combatted insurgent groups in the country.
The PDPA held its First Congress on January 1, 1965. Twenty-seven gentlemen gathered at Taraki's house in Kabul, elected Taraki PDPA Secretary General and Karmal Deputy Secretary General, and chose a five-member Central Committee (or Politburo).
However, the PDPA influence was largely limited to a small minority in the urban areas. Their influence gradually spread across the country mainly among the school teachers and military personnel. There are allegations from their opponents that PDPA had close ties with the Soviet Union.
Initially, the party did not use the name 'party', as there was no law on political parties at the time. It worked under the name 'People's Democratic Tendency' (Jerian-e Demokratik-e Khalq).
The banning of Khalq in 1966 prompted Karmal to criticize Taraki because of the newspaper's open expression of class struggle themes.
Karmal sought, unsuccessfully, to persuade the PDPA Central Committee to censure Taraki's excessive radicalism. The vote, however, was close, and Taraki in turn tried to neutralize Karmal by appointing new members to the committee who were his own supporters.
Karmal offered his resignation, and it was accepted by the Politburo of the Party. Although the split of the PDPA in 1967 into two groups was never publicly announced, Karmal brought with him less than half the members of the Central Committee.
In the spring of 1967 the PDPA formally divided into two factions. Subsequently, the two groups operated as separate political parties, each with its own Secretary General, Central Committee, and membership.
Taraki's faction was known as Khalq, after his defunct newspaper, and Karmal's as Parcham, after a weekly magazine he published between March 1968 and July 1969. Parcham was shut down in June 1969 on the eve of parliamentary elections, but the group had succeeded in getting some very powerful friends.
Both parties were consistently pro-Soviet. There are allegations that they accepted financial and other forms of aid from the Soviet embassy and intelligence organs. However the Soviets were close to King Zahir Shah and his cousin Dawood Khan - the first Afghan President - and it could have damaged their relations. There are no facts proving that the Soviets have provided financial help to either Khalqis or Parchamis. Taraki and Karmal maintained close contact with the Soviet Embassy and its personnel in Kabul, and it appears that Soviet Military Intelligence (Glavnoye Razvedyvatelnoye Upravleniye - GRU) assisted Khalq's recruitment of military officers.
In 1978 a prominent member of Parcham, Mir Akbar Khyber (or "Kaibar"), was killed by the government and his associates. Although the government issued a statement deploring the assassination, PDPA leaders apparently feared that Daoud was planning to exterminate them all. Shortly after a massive protest against the government during the funeral ceremonies of Mir Akbar Khaibar most of the leaders of PDPA were arrested by the government. Amin and a number of military wing officers of the PDPA Khalq wing stayed out of prison. This gave a chance to the group to organize an uprising. The government with the help of PDPA military members fell and the PDPA leadership was out of jail. Nur Mohammad Taraki, Babrak Karmal, and Hafizullah Amin overthrew the regime of Mohammad Daoud, and renaming the country the Democratic Republic of Afghanistan (DRA). The word 'Saur' means 'April' in Pushto.
On the eve of the coup, the police did not send Hafizullah Amin to immediate imprisonment, as it did with Politburo members of the PDPA on April 25, 1978. His imprisonment was postponed for five hours, during which Amin, without having the authority, instructed the Khalqi army officers to overthrow the government.
The regime of President Mohammad Daoud Khan came to a violent end in the early morning hours of April 28, 1978, when military units loyal to the Khalq faction of the PDPA stormed the Presidential Palace in the heart of Kabul. The coup was also strategically planned for this date because it was the day before Friday, the Muslim day of worship, and most military commanders and government workers were off duty. With the help of Afghanistan's military air force which were mainly Soviet made Migs 21 and SU-7's, the insurgent troops overcame the stubborn resistance of the Presidential Guard and killed Daoud and most members of his family.
The divided PDPA succeeded the Daoud regime with a new government under the leadership of Nur Muhammad Taraki of the Khalq faction. In Kabul, the initial cabinet appeared to be carefully constructed to alternate ranking positions between Khalqis and Parchamis. Taraki was Prime Minister, Karmal was senior Deputy Prime Minister, and Hafizullah Amin of Khalq was foreign minister.
Once in power, the party moved to permit freedom of religion and place agricultural resources under state control. They also made a number of ambitious statements on women's rights and waived the farmers debts countrywide. The majority of people in the cities including Kabul either welcomed it or were ambivalent to these policies. However, the secular nature of the government made it unpopular with religiously conservative Afghans in the villages and the countryside, who favored traditional Islamic restrictions on women's rights and in daily life. Their opposition became particularly pronounced after the Soviet Union occupied the country in late December 1979, fearing it was in danger of being toppled by mujahideen forces.
The U.S. saw the situation as a prime opportunity to weaken the Soviet Union, and the move essentially signaled the end of the détente era initiated by former Secretary of State Henry Kissinger. Funding for anti-Soviet Mujahideen forces began prior to the Soviet invasion, under the Carter administration, with the intention of provoking Soviet intervention (according to Zbigniew Brzezinski) and was significantly boosted under the Reagan administration, which was committed to actively rolling back Soviet influence in the Third World. The Mujahideen belonged to various different factions, but all shared a similarly conservative Islamic ideology, to varying degrees.
The Soviet Union withdrew in 1989, but continued to provide military assistance worth billions of dollars to the PDPA regime until the USSR's collapse in 1991.