Scottish Labour leader Iain Gray has quit after the SNP secured a historic majority in Holyrood.
The SNP secured the first majority in Scottish parliamentary history - an accomplishment many analysts had considered near impossible.
Soon afterwards, Mr Gray, who struggled to survive the vote in his own seat, announced he would step down in the autumn.
"I respect the decision Iain Gray has made today and I want to thank him for everything he has done for the Scottish Labour party," Labour leader Ed Miliband commented.
"This is clearly a very disappointing election result in Scotland."
Kirkcaldy, the seat whose result confirmed the SNP success, was the result which confirmed the SNP's majority. It saw a 12% swing in the SNP's favour, with the Scottish Liberal Democrats losing ten per cent of their vote share.
The Scottish Lib Dems lost 14 seats overall, but Labour also suffered with the loss of 11 seats.
SNP leader Alex Salmond said he hoped to introduce a referendum proposing independence for Scotland before the next elections, scheduled for 2016.
"It's likely the SNP have been showed trust by the people in a way no party ever has before in a Scottish election," Mr Salmond said.
"We'll take it forward to increase the powers of our parliament. In this term of the parliament we shall bring forward a referendum."
Swings from Labour towards the SNP averaged around 12 per cent - but the top-up seats mean the substantial shift may not be reflected in the final make-up of the new Holyrood parliament.
Prime minister David Cameron said the SNP win was "emphatic" but promised to fight the campaign for independence.
"On the issue of the United Kingdom if they want to hold a referendum I will campaign to keep our United Kingdom together with every single fibre that I have," he said.
In most areas, the SNP benefited by picking up support from the collapse of the Lib Dem vote, but Labour's share of the vote fell in several areas as well.
Among the seats the SNP gained from Labour, Strathkelvin and Bearsden saw a 20% swing towards the nationalists, Paisley saw a swing of 13% in their favour and Linlithgow registered an 11% swing towards the SNP.
Glasgow was a particularly fertile area for SNP gains against Labour, which saw Anniesland, Cathcart and Kelvin change hands.
Deputy leader Nicola Sturgeon held her seat with a healthy majority of 4,000. Most of the SNP holds saw comparable improvements in their majorities.
Scottish Labour leader Iain Gray, whose poor election campaign reached its low point when he was chased into a sandwich shop, managed to cling on with a majority of just 151 votes.
"Scotland has made a choice tonight. And although we cannot yet know for sure what the final shape of that choice is, the indications are clear," Mr Gray said in his victory speech.
"Given the opportunity, Labour would devote itself to those selfsame things which really matter... whatever the outcome of the election tonight, these will be Labour's priorities in the parliament in the five years ahead."
SNP gains included Airdrie and Shotts, Clydesdale, Cumbernauld and Kilsyth and Hamilton, Larkhall and Stonehouse.
Mr Salmond added: "It's clear from the indications that we've had so far that it's likely that the SNP have been restored trust by the people in a way no party ever has before in a Scottish election.
"We'll take that mandate and that trust forward to increase the powers of our parliament."
His demands included control of corporation tax, more borrowing powers and control of the crown's estates in Scotland.