463 Journal of Personality Disorders, 28(4), pp. 463–482, 2014 © 2014 The Guilford Press DISCRETE SUBGROUPS OF ADOLESCENTS DIAGNOSED WITH BORDERLINE PERSONALITY DISORDER: A LATENT CLASS ANALYSIS OF PERSONALITY FEATURES Vera Ramos, MSc, Guilherme Canta, PsyD, Filipa de Castro, PhD, and Isabel Leal, PhD Research suggests that borderline personality disorder (BPD) can be diagnosed in adolescents and is marked by considerable heterogene- ity. This study aimed to identify personality features characterizing adolescents with BPD and possible meaningful patterns of heteroge- neity that could lead to personality subgroups. The authors analyzed data on 60 adolescents, ages 15 to 18 years, who met DSM criteria for a BPD diagnosis. The authors used latent class analysis (LCA) to identify subgroups based on the personality pattern scales from the Millon Adolescent Clinical Inventory (MACI). LCA indicated that the best-fitting solution was a two-class model, identifying two discrete subgroups of BPD adolescents that were described as internalizing and externalizing. The subgroups were then compared on clinical and sociodemographic variables, measures of personality dimen- sions, DSM BPD criteria, and perception of attachment styles. Ado- lescents with a BPD diagnosis constitute a heterogeneous group and vary meaningfully on personality features that can have clinical im- plications for treatment. The DSM-IV-TR (American Psychiatric Association [APA], 2000) defines 10 categories of personality disorder (PD). Borderline personality disorder (BPD) is seen the most frequently in clinical practice, with a prevalence of This article was accepted under the editorship of Robert F. Krueger and John Livesley. From Hospital Garcia de Orta, Child and Adolescent Psychiatry Unit, Almada, Portugal (V. R.); Psychology and Health Research Unit, ISPA – Instituto Universitário, Lisboa, Portugal (V. R., I. L.); Lisbon Psychiatric Hospital Center, Lisboa, Portugal (G. C.); and National Institute of Public Health, Centre for Population Health Research, Cuernavaca, Mexico (F. d. C.) We appreciate the contributions made by the Hospital Garcia de Orta (Child and Adolescent Psychiatry Unit) and Hospital Dona Estefânia (Youth Clinic) for supporting this research project. We are indebted to the adolescent participants and their families for sharing infor- mation regarding their conditions. This study was supported in part by a PhD grant of the Portuguese Fundação para a Ciência e Tecnologia (FCT) (Grant SFRH/BD/31996/2006). Address correspondence to Vera Ramos, MSc, Psychology and Health Research Unit, ISPA – Instituto Universitário, Av. Elias Garcia – N. 31 – 4 D – 1000-148, Lisboa, Portugal; E-mail: verasantosramos@hotmail.com