The aim of this study was to report on the development and the initial validation of the Object Relations Rating Scale (ORRS), which is a measure of in-session enactments of object relations that draws on a psychodynamic conceptualization of personality organization. Forty participants were included in the study, distributed among neurotic, borderline and psychotic personality organizations (PO). Results showed that the interrater reliability of this new measure is good. Two tests of criterion validity support the validity of the measure: the ORRS discriminates well between the three PO groups and it correlates in expected ways with five PO dimensions. Finally, ORRS scales that pertain to the degree of in-session object relation enactments correlated with a measure of transference intensity (convergent validity), and correlations with therapists experience were low as expected (discriminant validity).