Montpelier /mɒntˈpiːliər/ is a city in Harrison Township, Blackford County, in the U.S. state of Indiana. This small rural community, the county's first to be platted, was established by settlers from Vermont, and is named after Vermont's capital city of Montpelier.

Montpelier was a central participant in the Indiana Gas Boom, as natural gas was discovered near the community in 1887. More importantly, the county's first successful oil well was drilled on the south side of Montpelier in 1890. Its population quickly grew from 808 in 1890 to about 6,500 by 1896. The Gas Boom, mostly an oil boom for Montpelier, gradually ended during the first decade of the 20th century.

Like many boom towns, the city's population has never matched that of the boom years. As of the 2020 census, Montpelier had a population of 1,540. However, the city's population stabilized many decades ago, and the community has multiple industries and an active community association. Montpelier is located near the former Godfroy Indian Reservation, and a statue of an Indian is featured prominently in the downtown district.

In 1836 and 1837, several groups of settlers from Vermont moved to East Central Indiana, and settled on the high ground on the south side of the Salamonie River. Abel Baldwin, a veteran of the War of 1812, was the leader of this group of Vermont natives. They named their community Montpelier, after the capital of their original home state. Baldwin and his son-in-law, civil engineer John Cook, surveyed the area in 1836, and it was platted on September 5, 1837. The original plat had 16 blocks with a total of 154 lots.

At the time Montpelier was settled, it was part of Jay County. The western portion of Jay County was split away in 1838 to form Blackford County. Montpelier was not the first community in what would become Blackford County – a village named Matamoras existed earlier. However, Montpelier was platted first, and Matamoras was essentially a ghost town after the 1880s.

Beginning in September 1870, the Fort Wayne, Cincinnati & Louisville Railroad connected Fort Wayne with Muncie, Indiana, and Montpelier was (and still is) on this line. With dramatically improved transportation for the community, Montpelier became incorporated as a town at the end of 1870. By that time, the town had grown to a population of 231.

In 1887, natural gas was discovered in Blackford County, and the area began its participation in the Indiana Gas Boom. While natural gas was found throughout Blackford County, crude oil was found mostly in the county's Harrison Township, which includes Montpelier. Blackford County's first successful oil well, located just south of Montpelier, began producing during 1890. Montpelier was thought to be "the very heart of the greatest natural gas and oil field in the world". By the mid-1890s, about two-thirds of Harrison Township (25 square miles) was considered part of an oil-producing region. Montpelier became a city where “money and whiskey flowed frequently”, and numerous other “recreational activities” were available. Oil production from the Trenton Gas and Oil Field surrounding Montpelier began decreasing during the first decade of the 20th century, and the Gas Boom (or Montpelier's oil boom) gradually came to an end. Montpelier began a return to normalcy and its population (like many boom towns) has never exceeded its Gas Boom peak.

The Montpelier National Bank was robbed by three men on the afternoon of August 4, 1933. The robbery lasted about ten minutes, and no shooting was involved. The robbers quietly left town, driving east on Indiana State Road 18, without being followed. It was later determined, by the Federal Bureau of Investigation, that the robbers were John Dillinger and the Dillinger Gang.