Campaigners will call on the Government tomorrow to ensure that every child has access to a good school library.
They are raising concerns that while some schools have a well-stocked and properly staffed library, many more do not.
It is not currently mandatory for secondary schools to have a library.
Authors, teachers, librarians, parents and pupils are expected to take part in the event at Westminster, meeting with MPs to press their case.
They argue that every child deserves access to the "knowledge and information that a good school library provides".
Lobby organiser Barbara Band, head of library and resources at the Emmbrook School, Berkshire, said that more than 120 people are expected to take part in the action.
She said she was "tremendously lucky" to work in a school that supports its library and to have seen how reading can inspire pupils.
"This mass lobby demands that all children should have this opportunity and that reading for pleasure should not be left to chance; it should be embedded and sustained in the school ethos," she said.
A Department for Education spokeswoman said: "We would like every school to have a well-stocked library and all secondary schools to employ a librarian, but this should be a local decision.
"It is up to individual schools to target their resources and to make their own choices about school library provision and book resourcing."