The aim of the study was to develop and preliminarily validate a self-completed questionnaire that could help in the assessment of families before and during psycho-educational interventions. The questionnaire was developed according to the cognitive-behavioural psycho-educational model. From an initial 38-item version of the questionnaire, a final shorter 24-item version was derived. The validation study of the final version was conducted on relatives of schizophrenic and schizoaffective patients: 31 for the test-retest reliability study and 92 for the confirmation of the subscales and convergent validity study vs. SF-36 and the questionnaire on Family Problems, PF. The final questionnaire showed good psychometric properties. The three-core dimensions of Problem-Solving, Communication Skills, and Personal Goals were clearly outlined in the items correlation analysis. The association with family burden and health-related quality of life was as expected. The FF provides a promising assessment of the family functioning pattern that is the object of psychoeducational family interventions. Further studies are needed to confirm the validity of the instrument, that could be helpful both in planning and in monitoring psycho-educational interventions and in mental health promotion projects.