Freemasonry is a fraternal organisation with practices deeply entrenched in tradition and history.
The Book of Constitutions, complied by Anderson and published in 1723 unites Freemasons all over the world.
All the regular Grand Lodges adhere to the principles therein. To change these constitutions to allow women to become members would require lodges throughout the world to agree to the change.
As cultures are so diverse and vary so dramatically in terms of social structure and gender relations, making this fundamental change would be extremely difficult.