Aliaga, officially the Municipality of Aliaga (, Ilocano: Ili ti Aliaga), is a municipality in the province of Nueva Ecija, Philippines. According to the , it has a population of people.
Originally known as Pulong Bibit, Aliaga became a town on February 8, 1849, and named after the Spanish hometown of its first gobernadorcillo, Aniceto Ferry. Aliaga, along with Cabiao, Gapan, San Antonio and San Isidro were transferred from Pampanga to the province of Nueva Ecija in 1848. It once included the present-day municipalities of Zaragoza, Quezon, and Licab. Kapampangans were the first settlers in the town, which was settled by the migrating Ilocano settlers.
Aliaga has a relatively cool and healthful climate, and is situated about midway between the Pampanga Grande and the Pampanga Chico rivers, in a large and fertile valley. Historically, the principal products were mostly crops such as rice, tomato, eggplant, and squash.
Aliaga is politically subdivided into 26 barangays, as indicated in the list below. Each barangay consists of puroks and some have sitios.
Tagalog and Ilocano are the major languages of the municipality. A minority of the population speaks Kapampangan.
The Taong Putik Festival is an annual festival held in the municipality on the feast day of Saint John the Baptist every 24th day of June. The religious festival is celebrated by the locals and devotees to pay homage to Saint John the Baptist by wearing costumes patterned from his attire. Devotees soak themselves in mud and cover their body with dried banana leaves. Devotees also visit houses and ask people for alms in the form of candles or money to buy candles which are then offered to Saint John the Baptist.
The Aliaga Schools District Office governs all educational institutions within the municipality. It oversees the management and operations of all private and public, from primary to secondary schools.