This thesis presents a study aiming to identify the selection criteria for the digitization of posters at the National Library of Sweden (Kungl. biblioteket). The theory is that cultural heritage institutions are empowered to decide how our cultural heritage is presented as they select what items (or, as in this study, posters) will be digitized. The poster is studied as it is an interesting media form which historically was an important means of communication. The poster can represent and reflect historical events and opinions in society. The posters chosen to be digitized, will represent a part of our cultural heritage as presented on the internet. The research questions are to find out the purpose of digitization, to identify the selection criteria, why the collection of posters is digitized, which posters have been chosen and what were the selections criteria. The study aims to compare principles with practice. Selection policy documents are studied and the poster collection is studied in documents, on the internet and by interviewing representatives at the National Library of Sweden. The conclusion is that although the policy documents are indeed thorough regarding detailed selection criteria, it is actually practical reasons (such as available resources) that finally decide what material is digitized. The situation that the cultural heritage institutions are constructing our visual cultural heritage is probably unavoidable, but the problem is that if choices are not made on the correct grounds, this will have the consequence that the presentation of our cultural heritage will not be representative.