Iba was founded by the order of Augustinian Recollect priest in 1611 the village of Paynauen. The early inhabitants of the town cosisted of several groups called Zambales. They were later joined by he Ilocanos who migrated to the town which resulted to intermingling of customs and traditions. A group of native called "Aetas" settled in the hinterlands and majority of them dwelled in the now famous Mt. Pinatubo.
   
In 1860, the administration of the town was turned over to the Dominican priests until the civil goverment came to power. There was no available records as to when Paynauen was renamed to Iba, but the old folks believed the town was named Iba after the sour fruit called Iba or commonly known as "Balimbing" are found abundant in the place.
   
Stories from elders on how the town got its name were handed from generation to generation. It was tolk that Spaniards came to the town who were wondering in the place to met a group of natives and asked what's the name of the place, they shouted "Iba, Iba" thinking that the man was asking what they are eating. From then on the place as called Iba.
   
Iba became permanent Capital of Zambales after Masinloc, because of its strategic location being on the central part of Zambales. Iba was described as blessed with glorious past. Iba was known its freedom loving people and long strech of sea, land with palm shaded shores, rice fields, rolling hills, and range of majestic mountain which comprises its wealth and natural resources.
   
On August 28, 1901, American Civil Governor William Howard Taft held the historic session of the second Philippine Commission that established the Province of Zambales under the American rule held at Iba Roman Catholic Church.

Iba which became famous in the world as the birthplace of the late President Ramon Magsaysay Sr.

Iba is Composed of 45 sitios, fourteen barangays, six of the barangays are located within the poblacion.