The talk pleads for a cooperation between citizens and scientists that is characterised by mutual respect, openness and genuine interest in the respective competences. In the keynote, psychological terms and approaches as well as various motivation theories, mod-els and studies are presented and discussed in relation to their relevance for Citizen Sci-ence. The researcher and consultant points out the contrast between the high interest in "participant motivation" and the low actual knowledge about it and gives possible reasons for this. She also shows the fine line between "motivation" and "manipulation". Successful projects clearly define different tasks within the project and analyse and communicate the goals and motives of all participants and consider them appropriately in the project. In this way, the diversity of competences and perspectives of all participants could be strengthened.