A transdiagnostic understanding of psychopathology is gaining increasing attention. Defense mechanisms can be understood as innerpsychic capacities to regulate the self strongly associated with mental health. Previously, defense mechanisms have been assessed using complex, resource extensive measures. Now a 30-item self-report Italian version has been developed to overcome this limitation. The aim is to investigate the psychometric properties of the German DMRS-SR-30 version to investigate associations with personality functioning and other related constructs to contribute to the advancement of a transdiagnostic understanding of psychopathology. A minimum of 490 adult participants will be recruited for this study. Participants have to meet the inclusion criteria: age 18 to 74 years and German language proficiency. Using a cross-sectional design, self-report assessments will be implemented in SoSci Survey, these will include DMRS-SR-30; personality functioning traits; mentalizing, epistemic trust and psychological symptom severity. The online survey will take approx. 25 mins to complete per participants.