The Oromo Liberation Front (Oromo: Adda Bilisummaa Oromoo, abbreviated: ABO; English abbreviation: OLF) is an Oromo nationalist political party formed in 1973 to promote self-determination and the independence for the Oromo people inhabiting today's Oromia Region and Oromia Zone in the Amhara Region of Ethiopia. The OLF has offices in Addis Ababa, Washington, D.C., and Berlin, from which it operates radio stations that broadcast in Amharic and Oromo.

The OLF is not to be confused with the Oromo Liberation Army, which is the now independent former military wing of the OLF. The OLA split from the OLF following disagreements over disarmament.

The Oromo people, an ethnic group native to the Oromia Region of Ethiopia, remained independent until the last quarter of the nineteenth century, when they lost their sovereignty and were conquered by Abyssinia. The Oromos suffered harsh oppression under the imperial rule of Haile Selassie, who was ethnically Oromo and Amhara. Under the Haile Selassie regime, the Oromo language was banned from schools and government. These changes initiated a period of Amhara cultural dominance lasting much of the twentieth century. Both the Haile Selassie and the Derg governments relocated numerous Amhara into southern Ethiopia, where they served in government, courts, churches, and schools, where Oromo texts were eliminated and replaced by Amharic ones. The Abyssinian elites perceived the Oromo identity and language as an obstacle to the expansion of Ethiopian national identity.

In 1967, the regime of Haile Selassie I outlawed the Mecha and Tuluma Self-Help Association (MTSHA) and later instigated a wave of mass arrests and killings of its members and leaders. Prominent military officer and leader of the association Tadesse Birru was also arrested. This reaction by the regime was caused by the popularity of the MTSHA among the Oromo, as well as its links to the Bale Oromo resistance movement.

One of the association's members, Hussein Sora, escaped to Somalia in 1967. He and other Oromo refugees formed a rebel group called the Ethiopian National Liberation Front, of which Sora was named Secretary General. The ENLF soon moved to Yemen and began training members of the Oromo diaspora.

The first attempt by the ENLF to enter the country was directed by Jaarraa Abbaa Gadaa, but it failed when Somali security forces tracked down the militants and arrested them while trying to enter Ethiopia through northern Somalia. The second attempt proved more successful and the second group of rebels made camp in the Chercher Mountains. At this point, the group decided to operate under the name "Oromo" instead of "Ethiopian."

In 1973, the political situation of the country had changed and the Ethiopian military had ousted the imperial regime and taken control. Leaders and members of the MTSHA, who had escaped arrest, had been operating secretly within the country by stirring up activism through underground newspapers such as "Kena Bektaa" and "The Oromo Voice Against Tyranny". They organized a secret conference which was attended by Hussein Sora, Elemo Qiltu and various other Oromo leaders. It was during this conference that the Oromo Liberation Front was officially formed and its first political program was first written out. The armed Oromo units in the Chercher Mountains were adopted as the military wing of the organization, the Oromo Liberation Army or OLA (Oromo: Waraanna Bilisummaa Oromo or WBO).

The Oromo Liberation Army in the Chercher Mountains was placed under the command of Hassen Ibrahim, more commonly known as Elemo Qiltu. In 1974, the OLA increased its activities in the mountains and caused much alarm amongst the administrators of the region especially when they killed the notorious landowner, Mulatu Tegegn. The military regime of Ethiopia then sent General Getachew Shibeshi to destroy the insurrection. On September 6, 1974, the first Oromo Liberation Army was obliterated by mortar fire in the Battle of Tiro in which they lost both Ahmad Taqi and Elemo Qiltu; only three OLA soldiers survived.