This article reviews the development and initial trial of a treatment for adolescents that targets negative emotionality and associated psychological difficulties--particularly anxiety and depressive disorders--as a more singular entity by utilizing an approach rooted in both emotion science and theory. The rationale for such an approach is based upon the perceived need for novel treatment approaches that target commonalities in emotional disorder symptom presentation and their intervention. Utilizing the "Unified Protocol for the Treatment of Emotional Disorders" originally developed for adults (Barlow, Allen, & Choate, 2004), we conducted a multiple-baseline design study of a slightly modified version of this protocol with three adolescents presenting an array of anxiety and depression symptoms. Adolescent participants in this preliminary investigation evidenced symptom reductions across disorders at posttreatment, with greater improvements noted at a 6-month follow-up. Based on these findings and research regarding the association between emotion science and developmental psychopathology, we detail a more extensive set of modifications to the protocol, undertaken in preparation for a subsequent open-trial investigation of the revised treatment. (Contains 2 tables.)