c. 1471. Portuguese explorers discover uninhabited islands of São Tomé and Príncipe.
1522. The islands become a Portuguese colony, and are eventually populated with slave labor from the African continent.
1800s. Two cash crops —cocoa and coffee—are introduced to the islands.
1876. Slavery is officially abolished.
1951. São Tomé and Príncipe become an overseas province of Portugal.
1975. São Tomé and Príncipe achieve independence from Portugal and select Manuel Pinto da Costa as president.
1984. São Tomé is proclaimed a nonaligned state, ending its special relationship with other socialist states.
1987. The constitution is amended to allow universal adult voting.
1990. A new constitution is approved by referendum and allows multi-party politics.
1991. First multi-party elections.
1994. Príncipe is granted political and administrative autonomy.