Preparations for the foundation of ZAVNOH started on December 5, 1942 when the Croatian representatives in AVNOJ requested the districtual boards to delegate members of the future Initiative Committee of the State Antifascist Council of National Liberation of Croatia. After the delegates were named the Initiative Committee was constituted in Ponor on March 1, 1943 near Korenica in Lika.
1st session
Held June 13 and June 14, 1943 was the founding session of ZAVNOH. Vladimir Nazor was chosen president. ZAVNOH adopted "Proclamation to Peoples of Croatia" and "Resolution". Resolution stated that ZAVNOH was highest political authority of anti-fascist movement in Croatia. Executive board of 11 members was elected to perform duties of ZAVNOH between sessions. As the representative of the Allied Command major William M. Jones was present at the founding session. Also the representative of the Liberation Front of the Slovenian People, Jana Jernej was present.
2nd session
The second session was held October 12–15, 1943 in Plaški. In this session an executive board of 15 members was elected and the decision of Executive Board of ZAVNOH made on September 20, 1943 was confirmed. "Ordinance About Interior Organisation and Work of ZAVNOH" was adopted as well as the Secretariat of ZAVNOH was founded; which ruled Croatian affairs as a de facto government. At the Second and Third sessions the equality of the Serbian and Croatian nations, as constituent nations of the federal unit of Croatia, was recognized in every aspect.
3rd session
The third session occurred on May 8 and May 9, 1944 in Topusko, and was sometimes referred to as the Sabor u Topuskom. The third session of ZAVNOH formally formed the Federal State of Croatia. Newly adopted "Rules of conduct of ZAVNOH" disbanded IO and formed 31 member Presidium of ZAVNOH. The following were established at this session:
Authorization of Croatian delegates on the 2nd AVNOJ meeting to represent Croatia
Proclamation of ZAVNOH as the supreme legislative and executive organ of government of Federal State of Croatia
Declaration of basic rights of peoples and citizens of the Federal State of Croatia:
* The Croat and Serb people in Croatia are equal in every way. The National minorities in Croatia will have guaranteed human rights.
* All citizens of Croatia are equal in the eyes of the law, regardless of their nationality, race and religion
* Women have the same rights as men
* Every citizen is guaranteed personal and property security. The right of ownership and private initiatives are guaranteed.
Decision about structure and operations of NLCs and assemblies in Federal State of Croatia
ZAVNOH operated in the City of Šibenik from December 31, 1944 to May 13, 1945, before moving to Zagreb on May 20, 1945.
The first People's Government of Croatia was founded at the extraordinary session of the Presidency of ZAVNOH, which was held on April 14, 1945 in Split.
