Adolescent Psychiatry Christopher M. Layne 1,* , Julie B. Kaplow 2 , Benjamin Oosterhoff 2 , Ryan M. Hill 2 and Robert S. Pynoos 1 1 UCLA/Duke University National Center for Child Traumatic Stress, and Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA, USA; 2 Department of Pediatrics, Baylor College of Medicine, Texas Children's Hospital, Houston, TX, USA  A R T I C L E H I S T O R Y Received: November 10, 2017 Revised: January 04, 2018 Accepted: January 23, 2018 DOI: 10.2174/2210676608666180306162544  Abstract: Background and Scope of the Problem. High prevalence rates of deaths by accidents, suicides, and homicides, coupled with expanding social networks, place adolescents at significant risk for traumatic bereavement occasioned by the traumatic deaths of their friends, romantic partners, and family members. Conceptual Analysis. This conceptual paper focuses on the interplay between posttraumatic stress symptoms and grief reactions that can arise following traumatic bereavement in adolescence. We begin with a review of “building block” key concepts needed to construct a scientifically sound and clinically useful theory of traumatic bereavement in adolescence. We briefly review earlier conceptual contributions and discuss the utility of unpacking and distinguishing between trauma exposure and bereavement as theorized causal risk factors, and posttraumatic stress reactions and grief reactions as their respective primary causal consequences. Multidimensional Grief Theory. We introduce multidimensional grief theory as a useful framework for conceptualizing a broad range of grief reactions, both adaptive and maladaptive, in traumatically bereaved adolescents. We use the theory to explore the interplay between posttraumatic stress and grief reactions, including ways in which each set of reactions may exacerbate the other and contribute to adverse outcomes. Implications for Evidence-based Assessment. We conclude with recommendations for trauma- and bereavement-informed risk screening, clinical assessment, and case formulation of potential consequences of traumatic bereavement in adolescence across multiple psychosocial domains. These domains include posttraumatic stress and grief reactions, school functioning, suicide ideation and behavior, risk-taking behavior, and developmental progression.  Keywords: Bereavement, grief, posttraumatic stress disorder, traumatic bereavement, adolescence, evi- dence-based assessment. 1. INTRODUCTION Bereavement is one of the most frequently re- ported adversities experienced by young people. The lifetime prevalence of minors bereaved by the *Address correspondence to this author at 11150 W. Olympic Blvd., Suite 650, Los Angeles, CA 90064, USA; Tel: (310) 235-2633 (x223); Fax: (310) 235-2612; E-mail CMLayne@mednet.ucla.edu death of one or both parents was 151 million worldwide in 2011 (UNICEF, 2013), not including bereavement by the death of other loved ones in- cluding siblings and other caregivers. Bereave- ment is also markedly prevalent in general popula- tion samples, with epidemiological studies consis- tently identifying bereavement as not only the most common, but also the most distressing type 2210-6774/17 $58.00+.00 © 2017 Bentham Science Publishers Send Orders for Reprints to reprints@benthamscience.ae 266 Adolescent Psychiatry, 2017, 7, 266-285 RESEARCH ARTICLE The Interplay between Posttraumatic Stress and Grief Reactions in Traumatically Bereaved Adolescents: When Trauma, Bereave- ment, and Adolescence Converge