Formed on 3 March 1953, it is the 38th largest in the United Kingdom based on total assets of £315 million at 31 December 2017.

An agency office (now closed) was opened in Stopsley in Luton in 2008, in September 2010 a fourth branch opened in Wendover, with a fifth in Tring in January 2011 and sixth in Buckingham in March 2011.

Accounts are also operated via post and online banking nationwide.

In 2015, 2016, and since 2017, each year it has won the What Mortgage Award for Best Local Building Society.

[3][4][5] The Harpenden Building Society is mentioned in The Poems of Ewen McTeagle, in Monty Python's Big Red Book (1971)[6]