In the early part of 1921, immigrants from central Luzon pioneered by the families of Nano Fabrigas and Espanol came into this large tract of virgin lands along the Pacific Coast via the jungle of Sierra Madre Mountains. Ilongots were the first inhabitants of the place.
The municipality of Dipaculao was accidentally created when while the Ilongots were having festivities of thanksgiving to commemorate the abundance of hunting and harvesting, Dipac, the Ilongot chieftain was drunk with Basi and Tuba, kind of native wine, fell on the ground. The Ilocanos who were present saw him fell, shouted: ni Dipac naulawâ, (Dipac got dizzy), hence born the name Dipaculao.
On 27 November 1950, Dipaculao was formerly a barrio of the municipality of Baler. The late President Elpidio Quirino made it into an independent municipality thru Executive Order No. 375. The late Anacleto Mijares was the first municipal Mayor who administered the transition of the municipality.
The municipality of Dipaculao was initially composed of 17 Barangays, viz: Poblacion, Mijares, Ipil, Salay, Bayabas, Mucdol, Buenavista, Diarabasin, Dibutunan, Borlongan, Dianed, Dinadiawan, Diamanen, Puangi, Lobbot, Toytoyan and Gupa. At present the municipality has twenty-five (25) barangays as a result of the addition of eight (8) more barangays including the split up of the Poblacion into two (2). The newly added barangays include the following: North Poblacion, South Poblacion, Laboy, Lipit, Maligaya, Sapang Kawayan, Diabuno, Diatale and Calaocan.
In 1952 the late Juan Roque assumed office of the first elected Mayor of Dipaculao. The late Florentino Velasco succeeded him from 1954 to 1980. After the retirement of the undefeated Mayor Velasco, who serves for twenty-six (26) years, his son Salvador Velasco succeeded him. After the EDSA revolution on 1986, an appointed office-in-charge, Mr. Crispin Paulino replaces Mayor Salvador Velasco. On 11 may 1982, a local election was held and gave Mayor Velasco another opportunity to administer the affairs of the municipality of Dipaculao, winning by overwhelming votes. He holds the position up to 1998. The synchronized local and national election in 1998 resulted to the change of administration where the Hon. Danilo A. Tolentino was elected as the municipal Mayor of Dipaculao.