The Midlothian and Peebles Northern by-election, 1929 was a parliamentary by-election held in Scotland on 1 January 1929 to elect a new Member of Parliament (MP) for the House of Commons constituency of Midlothian and Peebles Northern.
It was the first election to the Parliament of the United Kingdom to be contested by a candidate for a Scottish nationalist party.
The vacancy was caused by the death in December 1928 of the constituency's Unionist MP, Sir George Hutchison. He had held the seat from 1922 to 1923 and from 1924 until his death.
Four candidates were nominated.
The Labour Party nominated Andrew Clarke, who had held the seat from 1923 to 1924. The Conservaives nominated the industrialist John Colville, who had been the National Liberal candidate for Motherwell in 1922.
The local Liberal association selected 23 year-old David Keir as their candidate. He was the son of the Rev. T. Keir of Dumfries. He was educated at Dumfries Academy and Edinburgh University.