The new hi-tech secondary department at Ysgol Plas Brondyffryn, Denbigh, was officially opened this week by education and lifelong learning minister Jane Davidson.
Catering for around 60 pupils with autistic disorders, it will serve all of north Wales - yet no single education authority could have afforded such facilities on its own because so few of their own pupils would need it.
Around 1,622 Welsh youngsters with special needs go to schools outside their home council area, with some having to travel to England for specialised provision.
The Welsh Assembly has contributed pound;2 million and gifted a site for the pound;5m-plus redevelopment of Plas Brondyffryn, which will also include refurbished residential accommodation and a redeveloped primary department.
Headteacher Michael Toman said: "Denbigh doesn't generate enough autistic kids to justify this facility, but all of north Wales does. There needs to be a degree of collaboration between all authorities, especially when meeting the needs of children with low-incidence special needs.
"The Assembly has been the catalyst for this regional collaboration happening."
He said the new secondary department, physically linked to neighbouring Denbigh high school by a corridor, had enhanced opportunities for integrating and including special needs pupils in the mainstream.
"We have gone from the 19th to the 21st century and skipped the bit in the middle. We have gone from dilapidated to modern buildings, with whiteboards and a new information and communications technology suite, and it's no less than the children deserve.
"But we feel quite strongly it's a good idea because it promotes inclusion in practical ways. We have always had children attend Denbigh high for some lessons. Now some of our children with the most complex difficulties are going to the swimming club with the high school students.
"Ordinary children also benefit because it helps them grow, develop and understand more readily what special needs are all about. Some of the high school girls have done work experience in the office or with primary children."
Speaking at the secondary department's opening this week, Ms Davidson said:
"A large number of organisations and individuals have come together to form a strong partnership.
"Small local education authorities are sometimes faced with difficulties in developing such highly specialist provision, resulting in significant numbers of children being placed out of Wales - often at considerable distances from home.
"Plas Brondyffryn is the first of a number of regional projects. I want to compliment the six local education authorities which have had the foresight to see this regional approach through to fruition."