Externalizing traits are extremely costly for society and disproportionately prevalent among incarcerated individuals. The Hierarchical Taxonomy of Psychopathology (HiTOP) is an empirically derived classification system that approaches psychopathology dimensionally and was developed in response to critiques of current diagnostic classification systems. The Externalizing Spectrum Inventory–100 item version (ESI-100) is an assessment of externalizing problems that fits within the HiTOP framework and characterizes dimensional externalizing traits. The present study aimed to replicate prior research examining the convergent validity of the ESI Total Score by examining associations with psychopathy, conduct disorder, and substance use among incarcerated males. A total of 1,808 participants had ESI-100 data, although sample sizes across criterion measures varied. The majority of results replicated relationships between the ESI 159-item version and externalizing disorders and negative emotionality. Less is known about the dimensional relationships between externalizing traits as measured by the ESI-100 and internalizing disorders and symptoms, and other correlates of externalizing. The study extended previous results by examining associations between the ESI-100 and internalizing disorders, impulsivity, childhood trauma, and emotion regulation (ER) as a test of discriminant validity. Analyses revealed associations between the ESI-100 and childhood trauma, impulsivity, emotion regulation difficulties, and symptoms (but not diagnoses) of internalizing disorders. These results enhance our understanding of dimensional traits of externalizing and suggest nuanced relationships between externalizing and internalizing traits. Results have important implications (e.g., transdiagnostic treatment targets) for treatment of mental health disorders by highlighting the importance of cross-diagnostic treatment approaches. (PsycInfo Database Record (c) 2022 APA, all rights reserved)