When parents develop mental illness, children have a lot of questions and worries. The children are at a higher risk to develop mental illness themselves in later life. That is one of the reasons why it is important to monitor their uncertainty early on and to help them find answers to their questions. Among other things, child-appropriate media can be used here – for young children, ideally picture books to provide information on mental illness and on coping in daily life. Until today, little is known about children’s perception and processing of picture books. The aim of this study is to create a catalogue of criteria for picture books that provide helpful explanations of mental illness in parents and support children in their daily lives. The criteria will be roughly divided into content aspects, visual/pictorial and illustrative aspects, and language aspects. This will be done based on: (1) extensive literature research and theoretical exploration, and (2) interviews with experts. Then the criteria will be tested empirically by presenting children with a book selected from the catalogue developed and also by including many pictures and text examples from ther existing picture books in the survey.