Purpose: To explore the experiences and preferences of population-based research participants to whom an incidental finding was communicated. Materials and Methods: Of the 2580 participants of the Netherlands Epidemiology of Obesity (NEO) study who underwent magnetic resonance imaging (MRI) scanning of the abdomen, heart, and/or brain, an incidental finding with presumed health importance was disclosed to 56 (2%) participants. These participants were invited to discuss their experiences regarding the communication of the finding by the NEO research team in a focus group discussion. Transcripts of the discussions were analyzed using thematic content analysis with an open coding system. Results: Twenty-three persons participated in four discussions: 57% male; mean age 58 years; 74% findings were suspect for a malignancy. Overall, the participants were grateful for the disclosure of the incidental finding. They had assumed that any finding would be disclosed, and this was an important reason to participate in research. None regretted their informed consent to be notified about incidental findings. Disclosure of the finding had great impact on the lives of most participants. Difficulties with the transition from research participant to patient were frequently mentioned. Conclusion: This study provides information to improve the communication of incidental findings by 1) giving clear information about which findings will be disclosed, and 2) demarcating the transition from research participant to patient, by making clear arrangements with medical specialists to guarantee careful follow-up of the finding.