The alternative dimensional model of personality disorder (PD) diagnosis, based on personality‐functioning impairment and pathological traits, opens the door for tailoring treatments to individuals with more homogeneous personality profiles than diagnostic categories. Such a transdiagnostic PD treatment approach requires robust, replicable, personality‐relevant dimensions, which we found using a large battery of self‐report measures: Self‐pathology and negative affectivity (NA) traits, interpersonal pathology and detachment traits, and interpersonal pathology and antagonism traits. Using these dimensions, we identified three groups that had, respectively, elevations on (1) all three dimensions, (2) self‐pathology/NA (with/without interpersonal–pathology elevation(s)) and (3) either or both interpersonal‐pathology dimensions, without elevated self‐pathology/NA. Using the same personality‐functioning measures and a half‐overlapping trait set, we replicated these profiles in an additional sample. Interview‐based measures of functioning and personality pathology provided external validity evidence for the method, suggesting it represents a critical first step towards treatment research targeting transdiagnostic processes rather than diagnoses. For example, two groups might benefit from treatments focused, respectively, on emotional dysregulation and interpersonal relations, whereas the multiple‐problem group may need a sequenced treatment approach. Research is needed to test these hypotheses and to expand the method to include a wider range of pathological personality traits. © 2019 John Wiley & Sons, Ltd.