Perton First School's community gathered for the event on Wednesday evening which included a raffle and 70s music.
A new six foot owl mascot was also unveiled.
Stuart Randall is a member of the PTSA and parent to five-year-old Jacob who attends the school.
He said: "We were celebrating 40 years of the school being open.
"There was a raffle and music from 1979.
"The event was for people to come along and see what the school is all about.
"We've had a new plaque made for the school and we will be filling up a time capsule to bury in the next few weeks.
"Pictures of the school from the 70s were on show too, there were lots of things going on.
"The new school mascot was revealed too – a six foot fluffy owl.
"The school is exceptional in its own right.
"My wife attended the school just after it opened so it meant a lot to us that our son could go there too.
"I'm hoping it'll stay open for a long long time.
"We've also been trying to encourage more people to join the school's PTSA."
Headteacher Anne Bennett said about 100 people, including staff and students past and present came to the event. She said: "It was lovely. We had current pupils and parents, some of the parents were ex-pupils, we also had ex-staff and one of the former headteachers too, it was lovely to see.
"We're a very nurturing school, like a big happy family.
"It was such a fun day for the children, we had songs from the charts in 1979 playing all day.
"The children were singing along to Abba at lunch time and took it in turns dancing in the hall throughout the day.
"We really stepped back in time to 1979, it was just fantastic."