Multiphase Optimization Strategy (MOST) for Treating Pediatric Post-traumatic Stress Disorder (PTSD)

Inclusion Criteria: A child between the ages of 8-17 exposed to at least one DSM-defined trauma Child assent for participation The participation of a caregiver with custodial rights to provide parental permission Willing to participate in treatment delivery and respond to surveys Meet PTSD diagnostic criteria that is the result of exposure to at least one of the identified traumas Ability to read and understand English Willingness to be randomized to an experimental condition Placement in a stable caregiving environment for two months without an impending transition Children currently taking psychotropic medications must have taken the medicine without dose adjustment for two months prior to study entry. Caregiver or child with a smartphone capable of downloading a freely available software application. Exclusion Criteria: Psychiatric concerns requiring a higher level of care (e.g. suicidal ideation with intent; current psychotic disorder) An intelligence quotient (IQ) \< 70 Currently receiving a behavioral health intervention for concerns related to PTSD or pediatric trauma A participating caregiver who is a perpetrator of any identified trauma (e.g. sexual abuse) MRI contraindicators (e.g. presence of metal in the body)