Iraq and Syria are the only countries in which the party has risen to power.
Baath means "resurrection" in Arabic, and the party was initially conceived in Damascus by two French-educated schoolteachers in 1947.
The party took power in Syria in 1963, the same year the Iraqi branch helped overthrow then-leader General Abd al-Karim Kassem in a coup d'etat.
Despite the motto of unity, throughout the 1960s and 1970s attempts to unite the governments of Iraq and Syria failed due to a series of disagreements.
The Syrian party's first years in office were tumultuous, as disputes raged between military and civilian elements.
The military element eventually won in 1966, and there were a total of eight changes in leadership between 1963 and 1970 either in the party or in government.
Today, the party in Syria boasts 1.5 million members, out of a total population of 17 million.
Members are empowered to propose directions for the party but cannot make decisions during the congress, which is aimed at examining the overall situation of Syria's politics and economy.