Background: Symptoms description is often not enough to provide clinicians with guidelines for treatments and patients' clinical history does not represent an exhaustive source of data. Psychopathological dysfunctions are known to relate to the core disturbances that underlie different forms of psychopathology so the identification of such dysfunctions could be helpful for treatments. Some tools are available although highly complex and lengthy. This study aimed to provide clinicians with an easy-to-administer instrument able to capture different levels of impairment in psychopathological functioning, namely the Psychopathological Functioning Levels - Rating Scale (PFL-RS). Methods: The Psychopathological Functioning Level - Research and Training Committee (PFL-RTC) has been established in Turin since 2002 including psychiatrists and clinical psychologists with extensive clinical and research experience. Our research was grounded on the Qualitative Research Criteria (QRC) 1-7 and conducted with subsequent steps in order to identify those core psychopathological dysfunctions to be rated by this tool. Results: From 2002 until 2014, 316 outpatients were administered the clinical interview on at least two different occasions. Diagnoses were mixed and included: Schizophrenic and Psychotic Disorders, Depressive Disorders, Anxiety Disorders, Obsessive-Compulsive Disorder, Post-Traumatic Stress Disorder, Somatic Symptoms Disorders, Eating Disorders and Personality Disorders. Focus groups were conducted to identify those psychopathological dysfunctions which needed to be rated, according to two Phenomenological Selection Criteria (PhSC) and four Etiopathogenetic Selection Criteria (EtSC). As a result, five dysfunctional areas emerged: Identity (ID); Comprehension (CO); Negative Emotions (NE); Action-Regulation (AR); Social Skills (SS). After checking such dimensions for consistency with the existing instruments, 7 levels of severity were identified for each area. Finally, a provisional Italian schedule of Psychopathological Functioning Levels - Rating Scale (PFL-RS) was obtained and checked for semantic comprehension and then administered gathering preliminary data. Conclusions: Psychopathological dysfunctions underlying mental disorders have been recognized in the present study with the PFL-RS. This instrument seems promising to inform in a specific way treatments strategies and goals, specifically concerning psychotherapy. Notwithstanding, further research is needed in order to confirm validity, sensitivity and reliability of this instrument.