This study aimed to investigate predictors of vocational disengagement (referred to as Not in Employment, Education, or Training [NEET]) in young people with borderline personality disorder (BPD). The sample comprised 112 outpatients with a BPD diagnosis, aged 15–25 years, who participated in a randomized controlled trial (ANZCTR12610000100099). The proportion of participants who were NEET (39.3%) at study entry did not improve after 18 months and NEET status frequently changed. Therefore, multinomial regression analyses were used to study three groups: Non-NEET, NEET, and Unstable NEET status. NEET status was predicted by not achieving expected age-appropriate educational milestones, greater instability in identity, and emptiness. Greater instability in interpersonal relationships and identity predicted Unstable NEET status. The findings suggest that specific vocational interventions, that also incorporate a focus on interpersonal functioning, emptiness, and identity disturbance, are needed to improve functioning in youth with BPD, especially when educational milestones are not achieved.