In clinical child psychology, co-morbidity is the norm rather than exception. Single disorder manuals are limited in their scope and applicability to patients with several presenting problems. Emotion dysregulation and perfectionism are two salient pathways to various internalizing and externalizing mental health disorders in youth. In order to treat these children efficiently and effectively, psychotherapists must be equipped with an approach that is able to target these common corridors to psychopathology. Transdiagnostic modular cognitive behavioral procedures are matched to the individual patients’ contexts. The article begins with a brief discussion of emotional regulation, perfectionism, and transdiagnostic modular cognitive behavior therapy. Three confabulated clinical case examples are presented to illustrate the case conceptualization process and the application of modular CBT.