The government has published the question it plans to ask voters in a referendum on electoral reform.
Voters will be asked if they want to "adopt the 'alternative vote' system instead of the current 'first past the post' system" for electing MPs.
The referendum, part of the coalition agreement, is due to take place on 5 May next year.
The government is also proposing cutting the number of MPs from 650 to 600.
The plans are outlined in the Parliamentary Voting System and Constituencies Bill.
The full text of the question is: "Do you want the United Kingdom to adopt the 'alternative vote' system instead of the current 'first past the post' system for electing Members of Parliament to the House of Commons?"
Under the alternative vote (AV) system, voters rank candidates in their constituency in order of preference.
Anyone getting more than 50% in the first round is elected, otherwise the candidate with the fewest votes is eliminated and their backers' second choices allocated to those remaining. This process continues until a winner emerges.
The Liberal Democrats back a change to AV, but the Conservatives oppose it, and the two coalition parties have agreed that each will campaign for their own preferred system in the run-up to the referendum.
The bill, which has to be passed by Parliament before a referendum on AV is held, would also reduce the number of parliamentary seats from 650 to 600 and set up boundary reviews to create more equally sized constituencies.
Meanwhile, the Fixed-term Parliaments Bill, also introduced on Thursday, would mean general elections occur every five years on the first Thursday in May, rather than a date chosen by the prime minister.
Deputy Prime Minister Nick Clegg, who is overseeing the coalition's constitutional change programme, said the legislation showed that "fundamental reform of our politics is finally on the way".
He said: "The coalition government is determined to put power where it belongs - with people. You will decide how you want to elect your MPs.
"By making constituencies more equal in size, the value of your vote will no longer depend on where you live, and with fewer MPs the cost of politics will be cut.
"And, by setting the date that parliament will dissolve, our prime minister is giving up the right to pick and choose the date of the next general election - that's a true first in British politics."
Jenny Watson, chairman of the Electoral Commission, commented: "Our priority is making sure that everyone who goes to the polls on 5 May can cast their vote safely and easily whether it's in an election, a referendum or both."
The Electoral Commission is looking at the timing the referendum, which is due to take place on the same day as elections to the Scottish Parliament, Welsh Assembly, Northern Ireland Assembly and 280 local authorities in England.
Chairman Jenny Watson said: "It is possible to successfully deliver these different polls on 5 May, but only if the risks associated with doing so are properly managed."