Pupils from Lydgate Junior School in Crosspool took to the streets to show their opposition to council plans to shut Broomhill Library.
In a protest led by Year Six pupil Anna Mayer, aged 11, they sang and chanted as they made their way along Manchester Road to the library.
The school tailored its curriculum towards the demonstration - pupils composed a protest song, made the case in writing for keeping the library open and created banners in art and design.
Headteacher Stuart Jones said: “How on earth could a school pour cold water on children coming forward with an idea based on learning and culture?”
The council is consulting over its closure programme.