A big meeting of senior members of the Church of England will vote this week on whether to allow women to become bishops.
It could mean that Church rules that have been in place for thousands of years will be changed.
It's supported by the outgoing Archbishop of Canterbury and his replacement, the Rt Rev Justin Welby.
It could mean that women are allowed to take up some of the Church's most important roles in the future.
The vote comes 20 years after the Church decided to allow women to become priests.
Some are against change
While priests are normally in charge of churches, a bishop is in charge of a large area like a county - called a Diocese - with hundreds of churches.
Some people are against change because traditionally only men have been church leaders.
But others say there is no reason that women shouldn't be in the Church's positions of power.
If the Church's General Synod votes in favour of the change, the first woman bishop could start work in 2014.
If they vote against the plan, it could be years before the idea's put forward at the General Synod again.