Big Day Out is a 2012 World Book Day special book published by Jacqueline Wilson.

It contains 4 short stories; 2 featuring brand new characters, and 2 being sequels (of Lily Alone and The Worst Thing About My Sister). All the stories are about children and their siblings who go on a day out somewhere, whether it would be at the beach, a picnic, a fairground, or a cats show.

It is believed that at least one of the stories was originally featured in Totally Jacqueline Wilson.