A presentation from Museums and the Web 2009. In this paper, we address what mechanisms are at play when using on-line maps in a museum context to trigger and expand visitors’ involvement with an exhibition and its content. Our analysis is based on a comparison of two case studies carried out at Media Lab Helsinki in close cooperation with two museums in Finland: one with Kiasma, the museum of contemporary art in Helsinki, and the other with Design Museum Helsinki. Both made use of Open Source software (Urban Mediator and ImaNote) allowing users to leave comments in text or audio-visual format. These comments are visualized through the map components of the systems. To get maximum value from user participation, museums need to design a coherent network of participatory activies that include on-line tools. Session: Evaluation 2.0 [evaluation]