Objective To develop and test the psychometric properties of a measure of participation and social inclusion for individuals with a chronic mental disorder - the F-INK. Methods Within a cross-sectional design, mental health patients from different institutional settings (n = 106) and adults from the general population (n = 19) completed the questionnaire in an individual interview with a researcher. To estimate the reliability of two sum-scores on social inclusion and participation, Cronbach's α was computed. To appraise the validity, mean scale scores were compared across different study groups. Results For both scales, reliability was qualified as substantial (α > 0.70). Study groups showed expected differences in mean scores. Conclusion Preliminary findings suggest that the F-INK may be a useful tool for the assessment of social inclusion and social participation in individuals with a chronic mental disorder. However, further testing of the psychometric properties on a larger population is needed.