The general purpose of this dissertation is to study picture communication in picture books and it addresses the following questions:What is the illustrator?s role in the process of making a picture book? What communicative qualities do pictures have in picture books and how do pictures interact with texts? What methods do illustrators use to visualize the meaning of stories in picture books?A genre analysis, a literature study and an interview of a professional illustrator has been conducted to answer the questions. I found that all objects that make up pictures, the arrangement, colours and shapes contribute to the meaning in diverse ways. Pictures also communicate in a different way than texts. An important difference between pictures and texts in the context of picture books is that pictures are more open for interpretation.