Previously known as the Youth Advice Centre (YAC) that launched in 1992 on the corner of the then polytech site, it was initially staffed by a roster of health professionals who came into the community to provide social services for young people.
Now situated on Drews Ave, YST are a team of nurses, GPs, counsellors, social workers and youth workers.
The service is for people aged 10-25 who enter as self-referrals, walk-ins or referrals from GPs, schools, government agencies and other NGOs.
Earlier this year the Chronicle spoke to Children's Commissioner Judge Andrew Becroft who described New Zealand's youth suicide rate as a national tragedy.
"We have to confront that issue and the growing issue of mental health, and whether we have enough services, especially for teenagers.
"We do so well with so many children and young people but there's a small group that really troubles us and we can't ignore them."
But the services we do have are worth acknowledgement, he said.
Mr Sarten said the 25 year birthday for YST was a good time to celebrate what Whanganui has achieved and reflect on the many individuals and agencies who have supported YST over the years.
"The development of the service has, like many community initiatives, had times when it has to hold its financial breath while funding is found to keep the doors open.
He said now, thanks to various agreements, YST has a relatively stable funding base that ensures young people do have access to services when they are needed.
"This is critical as early engagement with support and services can make a huge difference to both immediate and long-term outcomes."
From 11am to 2pm on Monday, December 18, at Whanganui's Majestic Square there will be music from local young performers, games, a barbecue and of course birthday cake.