Adverse Childhood Experiences (ACEs) are traumatic experiences during childhood that may affect an individual's psychological development into adulthood. Previous studies have shown that ACEs are associated with an increased risk of various mental health problems, including Borderline Personality Disorder (BPD) tendencies. However, studies describing the experiences of ACEs among individuals with BPD tendencies remain limited, particularly in the Indonesian context. Therefore, this study aimed to describe the Adverse Childhood Experiences of individuals with Borderline Personality Disorder tendencies in Kupang City.This study employed a qualitative descriptive approach using thematic analysis. Four participants were selected through purposive sampling based on predetermined inclusion criteria. Data were collected through semi-structured interviews and analyzed using Braun and Clarke's thematic analysis. Data credibility was enhanced through member checking and source triangulationThese findings indicate that different forms of ACEs were interconnected and continued to influence the participants' lives into early adulthood. Emotional neglect emerged as the most dominant experience and was consistently reported by all participants. Furthermore, these experiences were associated with difficulties in emotion regulation, negative self-perceptions, and challenges in developing safe and trusting interpersonal relationships.