BACKGROUND: The mentalization-based perspective of Borderline Personality Disorder (BPD) underscores fluctuating interpersonal functionality, believed to arise from suboptimal mentalization modes, including hyper- and hypomentalizing. The connection between ineffective mentalizing and specific BPD challenges remains ambiguous. Network theory offers a unique means to investigate the hypothesis that distinct yet interconnected mental challenges ('symptoms') construct 'disorders' through their continuous mutual interactions. This study aimed to probe the pairwise interrelations between ineffective mentalizing and BPD challenges and to distinguish these relations between individuals with (clinical group) and without (community group) a BPD diagnosis using a network analysis approach. METHODS: Through a cross-sectional secondary data analysis, a moderated Mixed Graphical Model was employed on data from 575 individuals (350 clinical, 225 community). The study evaluated associations between ineffective mentalization modes (hypermentalization, hypomentalization, and no mentalization) gauged by the MASC and self-reported BPD-associated challenges, using BPD diagnosis as the moderating variable. RESULTS: The analysis confirmed the presence of significant links between ineffective mentalizing and specific interpersonal BPD challenges, which were moderated by BPD diagnosis. It implied that hypermentalization and hypomentalization might simultaneously shape BPD-associated challenges. CONCLUSIONS: The results offer fresh insights into the interplay between hypermentalization, hypomentalization, and BPD-related difficulties.