According to the 2002 census of the National Statistics Institute, Laja spans an area of 339.8 km2 (131 sq mi) and has 22,404 inhabitants (11,113 men and 11,291 women).

[3] Within the commune's territory are: Laja, its capital city; the villages of Las Ciénagas, Villa Laja and Las Playas; and the small villages of Puente Perales, Cantera, Violeta Parra, Cachapoal, La Colonia, Las Ciénagas, Diuquín, Picul, Santiago Chico, Quilales, Chillancito, Las Viñas, Las Lomas, Santa Elena, La Aguada and Arenas Muertas.

[6] As a commune, Laja is a third-level administrative division of Chile administered by a municipal council, headed by an alcalde who is directly elected every four years.

[1][2] Within the electoral divisions of Chile, Laja is represented in the Chamber of Deputies by Juan Lobos (UDI) and José Pérez (PRSD) as part of the 47th electoral district, together with Los Ángeles, Tucapel, Antuco, Quilleco, Santa Bárbara, Quilaco, Mulchén, Negrete, Nacimiento, San Rosendo and Alto Bío Bío.

The commune is represented in the Senate by Victor Pérez Varela (UDI) and Mariano Ruiz-Esquide Jara (PDC) as part of the 13th senatorial constituency (Biobío-Coast).