28th Congress of the CPSU (July 2, 1990—July 13, 1990) was held in Moscow

Moscow

Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent...

. It was held a year ahead of the traditional schedule and turned out to be the last Communist Party of the Soviet Union

Communist Party of the Soviet Union

The Communist Party of the Soviet Union was the only legal, ruling political party in the Soviet Union and one of the largest communist organizations in the world...

 (CPSU) congress in the history of the party.

• Mikhail Gorbachev
  Mikhail Gorbachev
  Mikhail Sergeyevich Gorbachev is a former Soviet statesman, having served as General Secretary of the Communist Party of the Soviet Union from 1985 until 1991, and as the last head of state of the USSR, having served from 1988 until its dissolution in 1991...
  
   was reelected General Secretary
  General secretary
  -International intergovernmental organizations:-International nongovernmental organizations:-Sports governing bodies:...
  
   (by a 3411 to 501 vote); Vladimir Ivashko
  Vladimir Ivashko
  Vladimir Antonovich Ivashko , was briefly the acting General Secretary of the Communist Party of the Soviet Union during the period from 24 August 1991 to 29 August 1991. On 24 August Mikhail Gorbachev resigned, and on 29 August the CPSU was suspended by the Supreme Soviet...
  
   was elected his deputy.
• A new Party Statute was passed, which formalized the end of the monopoly of power of the CPSU announced at the previous Party Conference.
• The New Union Treaty
  New Union Treaty
  Union of Sovereign States was the proposed name of a reorganization of the Union of Soviet Socialist Republics into a new confederation body. Proposed by Mikhail Gorbachev, the proposal was an attempt to avert the collapse of the Soviet Union. The proposal was never implemented in the wake of the...
  
   project was proposed by Gorbachev].
• Boris Yeltsin
  Boris Yeltsin
  Boris Nikolayevich Yeltsin was the first President of the Russian Federation, serving from 1991 to 1999.Originally a supporter of Mikhail Gorbachev, Yeltsin emerged under the perestroika reforms as one of Gorbachev's most powerful political opponents. On 29 May 1990 he was elected the chairman of...
  
   and some others resigned from the party after the "CPSU Democratic Platform" group failed to advance the transition to a parliamentary structure of the organization, while the "Marxist Platform" failed to oppose Gorbachev's reforms of "healing socialism
  Socialism
  Socialism is an economic system characterized by social ownership of the means of production and cooperative management of the economy; or a political philosophy advocating such a system. "Social ownership" may refer to any one of, or a combination of, the following: cooperative enterprises,...
  
   by capitalism
  Capitalism
  Capitalism is an economic system that became dominant in the Western world following the demise of feudalism. There is no consensus on the precise definition nor on how the term should be used as a historical category...
  
  ".
• The congress failed to issue the next Program
  Program of the CPSU
  The Program of the CPSU was the main document of the Communist Party of the Soviet Union which put forth the strategic plans for internal and external politics of the Party and the Soviet Union as a whole...
  
  , and issued only a Program Declaration.

The first Plenum

Plenary session

Plenary session is a term often used in conferences to define the part of the conference when all members of all parties are to attend.These sessions may contain a broad range of content from keynotes to panel discussions and are not necessarily related to a specific style of delivery.The term has...

 of the new CPSU Central Committee was held July 13-14, and with the exception of Gorbachev, a completely new Politburo

Politburo

Politburo , literally "Political Bureau [of the Central Committee]," is the executive committee for a number of communist political parties.-Marxist-Leninist states:...

 was elected.

Various organizations claiming to be the successor of the CPSU have held congresses continuing the numbering established by the CPSU and its predecessors. The Communist Party of the Soviet Union (1992)

Communist Party of the Soviet Union (1992)

Communist Party of the Soviet Union is a political party led by Sergei Skvortsov, operating in the countries of the former Soviet Union. The party was founded in 1992 at the so-called 29th Restorative CPSU Congress, which, among other actions, excluded Mikhail Gorbachev from the CPSU...

 held its so-called XXIXth Restorative CPSU Congress in 1992 declaring the CPSU reinstated. Similarly, the Union of Communist Parties — Communist Party of the Soviet Union

Union of Communist Parties — Communist Party of the Soviet Union

The Union of Communist Parties Communist Party of the Soviet Union is a group of communist parties in the former Soviet Union established in 1993, comprising:*Communist Party of the Russian Federation*Communist Party of Ukraine*Communist Party of Belarus*Communist Party of...

established in 1993, has also held congresses starting from XXIX, the most recent being XXXIIIrd Congress http://kprf.ru/kpss/kpss_people/.