Objectives:
The article presents the results of research on the Polish adaptation of the self-report questionnaires FFBI (Five Factor Borderline Inventory) and FFBI-SF (Five Factor Borderline Inventory – Short Form), which were developed to measure borderline personality traits.

Methods:
The study, which consisted of two sessions, included a non-clinical sample of N = 527 adults (session 1: N = 527; Mage = 32.74 years; SDage = 10.12 years; 44% male; session 2: N = 315; Mage = 33.56 years; SDage = 10.71 years; 48.6% male). For convergent and divergent validity, Borderline Personality Disorder Checklist (BPD Checklist), Screening Instrument for Borderline Personality Disorder (SI-Bord), Borderline Personality Inventory (BPI) and Personality Inventory for ICD-11 (PiCD) were used.

Results:
The results showed the Polish adaptations of the FFBI and FFBI-SF to be reliable and valid. Cronbach’s alpha coefficient for FFBI/FFBI-SF scales scores ranged from 0.80/0.67 to 0.94/0.91 (Mα = 0.89/0.84). The twelve-factor structure of FFBI/FFBI-SF items was conformed. All FFBI/FFBI-SF traits are related to borderline facets measured by BPD Checklist, SI-Bord, BPI and pathological personality traits measured by PiCD in an expected way.

Conclusions:
Obtained data demonstrate satisfactory internal consistency, factorial validity, and convergent-discriminant validity of the Polish adaptations of FFBI and FFBI-SF in a non-clinical sample.