Basilan (Chavacano: Provincia de Basilan; Cebuano: Lalawigan sa Basilan; Filipino: Lalawigan ng Basilan) is an island province of the Philippines within the Autonomous Region in Muslim Mindanao (ARMM). Basilan Island is the largest and northernmost of the major islands of the Sulu Archipelago. It is located just off the southern coast of the geographic Zamboanga Peninsula. Its capital, Isabela City, is a component city of Basilan, but is administered as part of the Zamboanga Peninsula Region.

Basilan is home to three main ethnic groups, the indigenous Yakans, and the later-arriving Tausugs and Zamboangueño. The Yakans and Tausugs are predominantly Muslim, while the Zamboangueño are mainly Christian. There are also a number of smaller groups. Although the official language is English, the major language is Yakan and lingua franca is Zamboangueño Chavacano, but other languages are well represented, including Tausug and Samal.

Basilan, although classified as a 3rd-class province in terms of gross provincial income, has one of the lowest incidence of poverty in the Philippines (26.19% of the general population), ranked 20 among the Philippines' 80 provinces (in comparison, Maguindanao which is ranked last at number 80 has a poverty incidence of 44.24%). The gap between Basilan's rich and poor residents are among the narrowest in the country (ranked 3rd nationwide), pointing to one of the most equitable distributions of wealth anywhere in the country (Gini coefficient 0.2826, which is slightly better than the Provinces of Pampanga, Bulacan, Nueva Ecija, Tarlac, Cavite, Batanes and Batangas).

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