The trouble of proving the effects of participation lies in the mismatch between three aspects of ownership: physical (possession), legal (ownership proper) and psychological (participation). In our interdisciplinary systemic model of ownership, we propose 10 relationships related to ownership/participation from: „A is a part of B” - greatest involvement to „A does not know about B” - the least involvement. „A” and „B” may take different values of: a person, an institution, a community, a group, an object (material, energetic, informational, purchasing). Once formalized we can view the studies in participation from one, system theory point of view, and formulate hypotheses related to many aspects of ownership. A multilevel analysis with multiple measures of both participation and effectiveness from two data sets has supported the proposed model.