Those aged under 27 are now able to join the Labour party for just a penny - but the Tories have poured scorn on the opposition's membership drive.
The offer, which is available until the end of polling day in 2011's local elections, is part of Ed Miliband's Speak Out For Your Generation campaign launched today.
Labour hopes to win over young people disaffected by the Conservative-Liberal Democrat coalition government's plans to scrap the educational maintenance allowance and hike tuition fees.
The party is also aiming to protect Sure Start centres which Labour fears are under threat, despite reassurances from David Cameron and Nick Clegg that they will be protected.
Mr Miliband used the launch to attack the comments made by Lib Dem ministers published in the Telegraph newspaper, claiming they demonstrated that the government was "well out on the right".
"These are decisions of a Conservative-led government propped up by Liberal Democrat passengers," he argued.
Shadow education secretary Andy Burnham said Labour's focus was on reaching out to young people.
"It's clear that Cabinet ministers won't stand up for young people. But Labour will - and that's what this campaign is about," he said.
"Today, Labour issues a Christmas invitation to young people: join us and we will be your first line of defence."
Labour points to school sports funding as an example of the impact it has already made from the opposition benches.
But Conservative party vice chairman for youth Andrew Stephenson dismissed Labour's appeal to young people.
"It was Ed Miliband's generation of Labour politicians who caused record youth unemployment and left the next generation paying the bills for Labour's legacy of debt," he commented.
"All Ed can offer is denial of the past and a blank sheet for the future."
Young MPs Chuka Umunna and Stella Creasy were among those attending the launch.