PMI Victorian History Library Inc. (Formerly Prahran Mechanics' Institute) is a community-owned subscription library situated at 39 St Edmonds Road, Prahran, Victoria, Australia. The library focuses on collecting resources about every locality in Victoria and every aspect of the history of the state. The library was previously situated in High Street, Prahran from 1915 to 2014 and Chapel Street, Prahran from 1854 to 1915. It is one of the oldest surviving Mechanics' Institutes in Victoria and one of only six still operating as a lending library. It was the only mechanics' institute in Victoria still governed by its own Act of Parliament. But in 2022 it incorporated as the PMI Victorian History Library Inc. under the Associations Incorporation Reform Act (2012).

The Institute spawned the Prahran Technical School, which went on to be one of Australia's leading art schools.

The Prahran Mechanics' Institute was established in 1854 in Chapel Street, Prahran by subscriptions and donations from the local community in an aim to facilitate lectures, discussions, a library, reading rooms, classes, and a museum.

In 1908 the Prahran Mechanics' Institute established the Prahran Technical School which operated firstly at Chapel Street, then at High Street from 1915 until 1971. In 2004 the High Street building was included in the Victorian Heritage Register for its architectural and cultural significance.

Since 1981 the PMI library has specialised as a Victorian history research collection and as the only lending collection of its kind in Australia.

In 2009 Prahran Mechanics' Institute sold the building located on High Street to Swinburne University of Technology. The PMI then purchased a building in nearby St Edmonds Road, Prahran and relocated in 2015.

The new and current PMI Victorian History Library at 39 St Edmonds Road, Prahran was officially opened by the Mayor of Stonnington, Cr Melina Sehr and PMI President Cr John Chandler OAM on 30 May 2015.

The PMI is run by a volunteer Board of seven people.