The MP for Liverpool Wavertree has quit the Labour party over what she calls "a culture of bullying, bigotry and intimidation".
Luciana Berger led seven MPs who all resigned from the party this morning, criticising Jeremy Corbyn's approach to leaving the EU and the leadership's handing of allegations of anti-semitism.
It's the most significant split to hit the party since the breakaway of the Social Democratic Party in the early 1980s.
The MP for Stockport, Ann Coffey, is also among the seven MPs to quit Labour, saying " I joined the Labour Party 41 years ago... I thought I would be in the Labour party for the rest of my life, but political parties are not an end in themselves."
Labour leader Jeremy Corbyn said "I am disappointed that these MPs have felt unable to continue to work together for the Labour policies that inspired millions at the last election."