Objective: The Personality Inventory for DSM-5 (PID-5) is the primary operationalization of the DSM-5 AMPD maladaptive trait framework. This study sought to examine the temporal stability of the PID-5 across one-year, as well as its concurrent and longitudinal associations with clinically relevant external criteria. Methods: Participants with heighted borderline personality features completed the PID-5 and measures of emotional, cognitive, and behavioral processes, as well as psychiatric symptomology, at baseline ( N = 107) and 1-year follow-up ( N = 72). Rank-order stability and mean-level changes for the PID-5 domains and facets were calculated, along with correlations with outcomes. Results: Results suggest high stability in terms of rank-order (median test-retest reliability estimate of .74 for domains and .70 for facets), but small to moderate mean-level changes were common. Prospective associations with clinical criteria suggest domains and facets are predictive of important therapeutic change processes and outcomes in theoretically expected ways. Conclusion: Findings generally support the stability of AMPD maladaptive traits and provide further evidence for the model’s clinical utility.