Stage Directors UK is to become a recognised trade union, the membership body has announced.
The move is the culmination of a process the organisation began 18 months ago.
As a trade union, it will look after the interests of stage directors, choreographers, movement directors, fight directors and intimacy coordinators.
Since first announcing its intention to become a trade union, SDUK's membership has grown by 25%.
Last summer, more than 90% of SDUK members who took part in a vote on whether to become a trade union, voted in favour.
A statement from SDUK said: "After numerous meetings with our members, partners in the UK and abroad and a thorough application process, UK-based stage directors now have what their American colleagues have had for decades: their own trade union.
"This is a historic achievement that will not only benefit SDUK members but the entire profession.
"SDUK looks forward to working with other trade unions to build a better, more resilient UK theatre."