The Spaniards introduced Christianity to the Filipinos and built numerous Catholic churches. One of these was established in Quingua (now Plaridel), of which Baliwag was originally a cabeceria or barrio with no definite name.

Due to limited transportation, the people of Baliwag had to walk or travel by banca to Quingua, a distance of about nine kilometers, to attend Sunday and feast day Masses. Because of this, churchgoers from Baliwag often arrived late. Their habitual tardiness became a subject of ridicule among the people of Quingua, who mockingly referred to them as “maliliwag” (slow or latecomers). When someone arrived alone, they would say, “Eto na si Ba Liwag,” with “Ba” being a term of respect for a man. Over time, the term “maliwag” evolved into “Baliwag,” a name that eventually identified the town itself and was even used by Spanish clergy in church announcements.

Baliwag was founded by the Augustinians in 1733, although historical records show that its formal creation was approved during the provincial chapter on May 15, 1734. According to Fr. Merino, both dates are valid: May 26, 1733 marks Baliwag’s actual or de facto establishment, while May 15, 1734 signifies its official recognition by the Augustinian Order. Baliwag was the tenth town founded by the Augustinians in the province of Bulacan.

Baliwag’s church, the San Agustin Church, recorded a total of 30 curates from 1733 to 1898. Among them, Fr. Esteban Diez Hidalgo and Fr. Fausto Lopez served the longest, with 40 and 24 years respectively. In his 1800 book Status of the Philippines, Augustinian friar Fr. Joaquín Martínez de Zúñiga described the convent or parochial house of San Agustin in Baliwag as the finest in the archipelago, noting that no building in Manila could compare to it in symmetry.

Fr. Martínez de Zúñiga arrived in the Philippines on August 3, 1786 and visited Baliwag on February 17, 1802 with Ignacio Maria de Álava y Sáenz de Navarrete. They were hosted by the parish priest at the time, Fray Esteban Diez. The powerful earthquake of June 3, 1863 caused significant damage to the church. Reconstruction began in 1870, starting with a temporary house of worship known as the “Provincial,” located southeast of the churchyard along Año 1733 Street. This simple structure was later used by the RVM Sisters of Colegio de la Sagrada Familia, now St. Mary’s College of Baliwag, as classrooms.

Antonio de Mesa, also known as “Maestrong Tonio,” from Makati, Rizal, was commissioned to create parts of the church, which were transported to Baliwag by river. During the early 19th century, Baliwag was considered one of the largest and wealthiest towns in Bulacan. Its locally woven piña fabrics and cigar cases (petacas) even earned international recognition when the Philippines won prizes at the London Exposition of 1851.

Baliwag’s first recorded local executive was Capitan Jose de Guzman, who served as gobernadorcillo, the highest civil position open to Filipinos at the time. The gobernadorcillo was responsible for collecting tributes, maintaining local jails, feeding prisoners, and supporting municipal needs—often at personal expense. He was assisted by a tribunal composed of a teniente mayor, juez de ganadas, and juez de policia.

With the enactment of the Maura Law in 1893, the title gobernadorcillo was changed to capitan municipal, while jueces became tenientes. From Baliwag’s separation from Quingua (Plaridel) until 1898, the town recorded 49 capitanes, 13 alcaldes, and 92 gobernadorcillos. Felix de Lara (1782) and Agustin de Castro (1789) were the first alcalde and gobernadorcillo, respectively. In 1908, Municipal President Fernando Enrile honored several former chief executives by naming streets after them.

On May 1, 1899, troops under General Henry Ware Lawton, composed of 25 scouts, marched into Baliwag from Norzagaray and Angat to reinforce their forces. On the same day, U.S. Secretary of State John Hay handed over 20 million US dollars to French Ambassador Jules Cambon as payment to Spain under the Treaty of Paris for the cession of the Philippines.

The American regime introduced significant changes in Baliwag, particularly in governance, education, language, and currency. The Mexican peso was replaced by American-issued coinage, symbolizing the new colonial authority. These reforms left a lasting impact on local administration and public institutions.

Baliwag was chosen as the site of the first municipal elections in the Philippines, held on May 7, 1899, under the supervision of Philippine-American civil and military authorities. After attending Holy Mass, voters gathered at the plaza of San Agustin Church, where officials were selected based on qualifications imposed by the American administration.

According to local accounts, the first municipal building during the American period was the Yoyongko family residence in Poblacion. This property later became part of the public market site purchased from Mariano Yoyongko, who had served as gobernadorcillo in 1885–1886 and as capitan municipal in 1891.

When the municipio burned down in 1907, the local government temporarily rented the large Gonzalez house along Sta. Leocadia Alto, owned by Jose Gonzalez, brother of Dr. Joaquin Gonzalez, also known as “Pepeng Mariquita”. In 1915, the government purchased the property, which then served as the Lumang Munisipyo or old town hall for 65 years. Today, this historic building houses the Baliwag Museum and Library.

On New Year’s Eve of 2000, Baliwag welcomed the new millennium with a memorable celebration held in front of San Agustin Church in Barangay Poblacion. Shortly before this event, National Artist Nick Joaquin described Baliwag as an “almost city” in his December 20, 1999 article Baliwag the Almost City, published in the Philippine Graphic. He characterized the town as a “super exurbia—still clean and green ecologically—and a magnet for the urban and suburban population of Metro Manila,” a description that continues to reflect Baliwag’s growth and character today.