In acknowledgment of the continued tension between the need to dimensionalize personality pathology in youth, and the reality of a categorical nosology in clinical settings, the goal of the present chapter is to review research on child and adolescent personality pathology from both these perspectives. While the review highlights several differences in constructs, methodology, and clinical implications of the two approaches, it also highlights significant commonalities in conclusions drawn from the traditions underlying categorical versus dimensional approaches. In particular, both categorical and dimensional approaches seem to support the idea that adolescence presents a unique developmental period for the crystallization of personality pathology.

This rejoinder is aimed at responding to the respective commentaries by Vernberg and Abel and Beauchaine; however, most of the rejoinder focuses on the commentary by Vernberg and Abel given the fact that Vernberg and Abel appear to challenge the basic premise that maladaptive traits denote personality disturbance beyond that of externalizing and internalizing disorder, which according to them, renders the concept of youth BPD obsolete. The authors of this rejoinder provide two points of rebuttal in this regard. First, while it is true that Axis I and II show a very similar empirical structure and can thus be represented from a unified perspective, the construct of youth BPD lies in the co-occurrence and interplay of specific symptoms. BPD is therefore more than a sum of its symptoms, and assessing these symptoms individually from established internalizing-externalizing measures (as Vernberg and Abel suggest) would not adequately capture the dynamics between symptoms that largely account for the downward spiral of BPD functioning. Second, they view the DSM-5 Criterion A function as the feature of personality pathology that distinguishes it from trait function; in particular the self-concept manifestations of Criterion A that are not readily captured by trait (Criterion B) personality function.