Dolores as we know it today was a settlement formerly called Bucao. The place was named after the chieftain of the first settlers who were Itnegs. Bucao was already an organized settlement as early as the first part of the 17th century. Its first recorded history was in the year 1615 when Fr. Juan Pareja established a small bamboo church and a convent in the area. The parish of Tayum supervised the mission since the town of Tayum has then the political jurisdiction over the place. Years later, a group of dark-complexioned people settled in the area now called Isit, a derivation from the Ilocano word Nangisit, which means black. And as migration took place, different groups of Ilocano settlers from Ilocos Sur, Bangued and Tayum established their homes in the villages in and adjacent to Bucao.

Bucao was a big barrio of Tayum during those times. In the year 1882, on the recommendations of the parish priest of Tayum, Fr. Pio Mercado and the Teniente Bazar of Bucao, Ignacio Eduarte, Bucao was organized into a pueblo. The political jurisdiction of the pueblo was Isit, Modi-it, Talogtog and Pakak.

In 1884, Rosalio Eduarte, the son of Ignacio, became the gobernadorcillo. A year later, in 1885, Bucao was renamed Dolores in honor of the wife of the Spanish Governor  who incidentally also donated an image of the Nuestra Señora delos Dolores which the town was dedicated to.

The first local executive of the town was Don Rosalio Eduarte. Capitan Ayyong as the people fondly called him was great and popular. Aside from becoming the gobernadorcillo, he also served as member of the town council, providing the necessary guidance to the body. He also became the governor of the sub-province of Abra.

The revolution against Spain that swept the country in the last part of the 20th century has drove away the Spanish missionaries including those stationed in Dolores. For about two years, no replacements could be made to undertake the missions. It was in 1898, when a few secular priest from Vigan came to Abra and occupied at least the main missions. Dolores received one of them in the person of Fr. Sinforoso Bunuan.

It was also during those years that the Aglipayanism was strong. Fr. Sinforoso Bunuan was even converted to that religion and with him, the whole town became Aglipayan. The town became a strong hold of Aglipayanism. All the influential people were staunch supporters of Aglipay. Rosalio Eduarte even pledged adherence to the sect by signing the document with his own blood. Many others had followed his example.

The government officials had confiscated the old two-storey convent. They converted it into a municipal hall. This served as the municipal hall of the down until after it was destroyed by earthquake in 1990.

On February 28, 1929, one of the most important changes in the history of Dolores took place. San Juan its largest barangay was separated and made into a new municipality by legislative action. It was the first bill of then Congressman Quintin Paredes. Prior to that, Dolores was then the second largest municipality to Bangued in terms of income.