Guests included Jackie McKiernan who, as Wanneroo MLA Jackie Watkins, helped start the group, and Wanneroo Mayor Tracey Roberts.
Children enjoyed cooking, play dough, bubbles, balloons and face painting, and everyone could add pieces to a commemorative mosaic.
‘Feedback was excellent and many people stayed to enjoy the sunshine, catching up with friends and the sausage sizzle,’ president Becky White said.
Sponsors included Lotterywest, the City of Wanneroo and local businesses.
Two local mothers started the group with about eight children in 1973, offering sessions in their own homes.
Now based at Wanjina Crescent, the playgroup is one of WA’s largest, with about 200 children attending weekday sessions.