Prahran Mechanics' Institute (PMI) is a subscription library situated at 39 St Edmonds Road, Prahran, Victoria, Australia The library was previously situated in High Street, Prahran (1915-2014) and Chapel Street, Prahran (1854-1915). The Prahran Mechanics' Institute was established in 1854 in Chapel Street, Prahran by subscriptions and donations of the local community. It is one of the oldest surviving Mechanics' Institutes in Victoria and one of only six still operating a lending library. It is the only mechanics' institute in Victoria still governed by its own Act of Parliament.
In 1908 the Prahran Mechanics' Institute established the Prahran Technical School which operated firstly at Chapel Street, then at the High Street site from 1915 until 1971. In 2004 the High Street building was included in the Victorian Heritage Register for its architectural and cultural significance.
In 2009 the PMI sold the High Street building to the Swinburne University. The PMI then purchased a building in nearby St Edmonds Road, Prahran and relocated in 2014.
Since 1980 the PMI library has specialised as a Victorian history research collection and as the only lending collection of its kind in Australia. More recently it also collects Australian history and interstate local history publications.
Keith Dunstan OAM was patron of the PMI 2009-2013.
In the long tradition of mechanics' institutes, Prahran Mechanics' Institute runs a programme of educational activities including free public lectures. It also operates Prahran Mechanics' Institute Press, a not-for-profit publishing service for authors of works about aspects of the history of Victoria.