Borderline Personality Disorder (BPD) is a severe disorder characterized by impulsivity, instability, emotional dysregulation and Non-Suicidal Self-Injury (NSSI). These features might be identified in adolescence and develop over time. Early identification is the first step to prevent the development of borderline features to a personality disorder. The purpose of this study was to validate the Portuguese versions of the Borderline Personality Features Scale for Children (BPFS-C) and the Borderline Personality Features Scales for Parents (BPFS-P). The psychometric properties of the scales were tested in two samples of adolescents (N = 256; N = 441) and a sample of parents (N = 259). Each scales’ confirmatory factor analysis revealed the same unidimensional structure of the original versions, showing adequate fit indices and an acceptable internal consistency. Correlation results demonstrated satisfactory convergent validity for both versions. Measurement invariance of the BPFS-C across sex showed configural, metric and partial scalar invariance. Overall, the BPFS-C and BPFS-P are both valid and reliable measures to assess borderline features in adolescents. Employing them in clinical and educational settings might contribute to early detection and initial referral to adequate treatment.
