The Mali Federation (Arabic: اتحاد مالي) was a federation in West Africa linking the French colonies of Senegal and the Sudanese Republic (or French Sudan) for two months in 1960. It was founded on 4 April 1959 as a territory with self-rule within the French Community and became independent after negotiations with France on 20 June 1960. Two months later, on 19 August 1960, the Sudanese Republic leaders in the Mali Federation mobilized the army, and Senegal's leaders in the federation retaliated by mobilizing the gendarmerie (national police); this resulted in a tense standoff, leading to Senegal's withdrawal from the federation the next day. The Sudanese Republic officials resisted this dissolution, cut off diplomatic relations with Senegal, and defiantly changed the name of their country to the Republic of Mali. During the brief existence of the Mali Federation, Modibo Keïta, who would later become the first President of Mali, served as its premier, and the government was based in Dakar, the eventual capital of Senegal.

After World War II, the colonies of French West Africa began pushing significantly for increased self-determination and to redefine their colonial relationships with France. Following the May 1958 crisis, the colonies of French West Africa were given the chance to vote for immediate independence or to join a reorganized French Community (an arrangement which would grant the colonies some self-determination while maintaining ties to France). Only Guinea voted for full independence, and the other colonies of French West Africa voted to join the French Community.

In the 1958 election to decide the issue of independence, two major parties split the countries of West Africa: the African Democratic Rally (French: Rassemblement Démocratique Africain, also known as the RDA) and the African Regroupment Party (French: Parti du Regroupement Africain, commonly known as the PRA). The two regional groupings of parties struggled against one another on the issue of independence and the extent of ties with France. The RDA was the governing party in the Ivory Coast colony, the French Sudan colony, and Guinea, while the PRA was a major governing party in Senegal and had sizable majorities in many countries. The two parties were also part of coalition governments in French Upper Volta, Niger, and French Dahomey. Both parties struggled with each other to shape the political future of the region; Mauritania often became a neutral party that would break any deadlocks. The vote of 1958 revealed a number of divisions within the parties. The RDA held a congress on 15 November 1958 to discuss the recent election results, and the division became clear with Modibo Keïta from French Sudan and Doudou Gueye from Senegal arguing for primary federation, which would include France and the colonies in a unified system, and Félix Houphouët-Boigny of the Ivory Coast dismissing that idea. The resulting deadlock was so severe that the meeting was officially said to have never taken place.

In late November 1958, French Sudan, Senegal, Upper Volta, and Dahomey all declared the intention to join the French Community and form a federation linking the four colonies together. French Sudan and Senegal, despite longstanding divisions between their main political parties, were the most enthusiastic pushers for the federation, while Dahomey and Upper Volta were more hesitant in their desire to join the federation. French Sudan called for representatives of each of the four countries (and Mauritania as an observer) to Bamako on 28 to 30 December to discuss the formation of the federation. French Sudan and Senegal were the leaders at the congress, with Modibo Keïta named the president of the meeting and Léopold Sédar Senghor of Senegal being the key leader on many issues, including the development of the name Mali Federation for the proposed union.

Although Upper Volta and Dahomey declared formal support for the federation, and Upper Volta even approved the Mali Federation Constitution on 28 January 1959, political pressure from France and the Ivory Coast, both of which opposed the federation, although for very different reasons, resulted in neither ratifying a constitution that would include them within the federation. The result is that only the colonies of French Sudan (now called the Sudanese Republic) and Senegal were engaged in the discussions of the formation of the federation by 1959.

Elections in March 1959 in both French Sudan and Senegal cemented the power of the major parties, while pushing for the formation of a federation. Keïta's Union Soudanaise-Rassemblement Démocratique Africain (US-RDA) won 76% of the votes in French Sudan and all of the seats in the territorial assembly. Senghor's Union Progressiste Sénégalaise (UPS) won 81% of the vote and all of the seats in Senegal's territorial assembly. Although Senghor won the elections by a large margin, some conservative Islamist marabouts supported the candidacy of Cheikh Tidjane Sy. That challenge to Senghor's party showed some of the weakness in Senghor's domestic political base and required a complex system of alliances with various domestic constituencies, both of which would become important as the federation progressed. Sy was arrested on election day because of some rioting, which was blamed on his party.

After the elections, the assemblies of Senegal and French Sudan approved the federation and began the process of constructing a political system to unite the two colonies. That involved three different political projects with the principle of parity (even representation from both colonies) enshrined in each' a federal government, united social movements (a labour and youth movement), and a shared political party for both countries. The federal government would have a federal assembly composed of 20 members from each of the colonies (40 in total), a President (set to be elected in August 1960), and six federal ministers (with 3 from each colony). Until a president was elected, the premier of the Mali Federation was to be Keïta, and the vice-premier (and the person in charge of the armed forces) was to be Mamadou Dia from Senegal. Furthermore, as part of the parity principle, any legislative initiatives required a signature by both the premier (then later the president) and the minister responsible for that issue. The colonies were to share the import and export taxes raised in the port of Dakar between them to the advantage of French Sudan, which had almost a third of its 1959 budget provided by that tax income.

At the same time, the Mali federation sought to create unified social organisations to facilitate the union between the countries. That involved creating labour movements and youth movements to operate at both the federal and national levels, as well as a unified political party. The political party was the major project as the ruling parties in both colonies combined to form the Parti de la Fédération Africaine (PFA). It was organised separately from the federal government but with many of the same members and leaders. Senghor was the party president and Keïta was the secretary general. In addition, to have a regional influence, Djibo Bakary of Niger and Emile Zinsou of Dahomey were named the vice-presidents of the party. As articulated at the first PFA congress in July 1959 by Senghor, it would be the single political party in the country and aimed to unite across the different ethnic groups in the territory.