The Septennial Act 1715 was an Act of the Parliament of the Kingdom of Great Britain in 1715, to increase the maximum length of a Parliament (and hence between general elections) from 3 years to 7 years.

The previous limit of 3 years had been set by the Triennial Act 1694 in the Kingdom of England. The ostensible aim of the Act was to reduce election expenses, but it also had the effect of keeping the Whig party, who had won the 1715 general election , in power for longer - and they won the eventual 1722 general election .

It did not require Parliaments to last that long, but merely set a maximum length on their life. Most Parliaments until the formation of the United Kingdom of Great Britain and Ireland did indeed last 6 or 7 years, with only two lasting for less time.

The Act was amended in 1911 by the Parliament Act 1911 to change the limit to five years, and then again during the Second World War to extend the Parliament elected in the 1935 general election until the European war had ended in 1945.

See also: List of Parliaments of Great Britain, List of Parliaments of the United Kingdom