The Illustrated Index of Imagined Animals was developed for the 2014 Children's Book Festival, a partnership between State Library Victoria and The Wheeler Centre. Inspired by author and illustrator Marc Martin, The Illustrated Index of Imagined Animals was installed in the historic Cowen Gallery of State Library Victoria and actively engage participants in the creation of a giant collaborative book. Engaging children 12 and under, The Illutrated Index of Imagined Animals created opportunities for children to participate directly in the key aims of the Festival: to link the community with literacy, literature and learning through an immersive festival experience. I designed the format and content of the activity, which included two key components: participants created an 'imagined animal' using collage materials and added it to the 'page' of the giant book which reflected their animal's habitat. On the reverse side of the concertina pages, participants classified their animal on an index card and added a short story about their character to create an index of everyone's 'imagined animals'. In order to further extend engagement and celebrate the collaboration, each page was photographed at the completion of the Festival and a pdf version of the 'book' designed. This was then emailed out to all participants.