The law that bans a British monarch from marrying a Catholic is to be lifted after more than 300 years.
The reforms were announced following the unanimous agreement of the 16 nations that have Queen Elizabeth II as their constitutional head of state.
But they will not include the repeal of a Catholic becoming monarch because allegiance to the pope might conflict with the sovereign's role as the supreme governor of the Church of England.
The changes will also see the end of the ancient tradition of male primogeniture, the rule under which boys take precedence in the line to the throne over elder sisters.
Catholic leaders in Britain welcomed the announcement.
Archbishop Vincent Nichols of Westminster said the move will eliminate a point of unjust discrimination against Catholics.