The expansion of participatory design, from a Scandinavian workplace context, to also include the public sphere, communities and developing countries, has led to a high diversification of participants. However, these new types of participant groups are often addressed in a simplistic manner, viewed as homogenous entities, without consideration being given to the fact that they may consist of subgroups and individuals, all with different needs and preconditions to participate. Further, there seems to be little understanding of the fact that people’s situations are not static, but changes over time as a project unfolds. In this article, it is argued that focus needs to be put on reflection of participant diversity and changeability over time. An example is given of how a tool for reflection can facilitate this, give visual form to complex situations, highlight differences between groups and indicate how participants’ positions alter over time. It is proposed that the tool can enable design researchers to reflect collectively about how different groups should be involved, as well as on the effect that project actions and decisions can have on participants.