Chris Myant, director of the Commission for Racial Equality (CRE) Cymru, said Cwmlai primary school in Tonyrefail had succeeded in coming up with creative and innovative ways to celebrate diversity.
Susan Williams, headteacher, had made it a priority to teach pupils about other cultures and religions when she was new in post, he added.
"She used to work at a school that had pupils from 14 different backgrounds. I think she was amazed at how little the children at her present school knew about cultural diversity."
Last year, pupils at Cwmlai took part in a massive "One world, our world"
project, involving visits from artists from different communities, food-tasting, music, art, storytelling and dancing.
This culminated in an exhibition opened by Jane Davidson, the education, lifelong learning and skills minister.
Mrs Williams said: "I was very keen people didn't think you do multicultural or diversity education by just having an event. It's something that has to be done across the curriculum, across the life and ethos of the school. "
Cwmlai also hosts visits from pupils from her old school, and uses life-size "persona" dolls - including one of a Sikh boy called Ravinder, who loves crisps - to challenge racial stereotypes.