Brief Title Mechanisms of Cancer-Related Pain and Opioid Use Among Adolescents and Young Adult Sarcoma Survivors: Pilot Feasibility Study

Inclusion Criteria:

* All genders between the ages of 12-24 (inclusive) at sarcoma diagnosis.
* Any age \< 70 at the time of study enrollment.
* No evidence of disease and/or enrolled in survivorship care.
* Clinically meaningful pain related to disease or its treatments at baseline (defined as 3 or greater on a 0-10 Numerical Rating Scale).
* Willing to attend the baseline appointment in person.
* Access to internet-capable smartphone.
* Access to internet on an occasional basis.
* Willing and able to complete Ecological Momentary Assessments (EMAs) on internet-capable smartphone for a 3-month period after enrollment.
* Ability to understand and provide informed consent/assent.

Exclusion Criteria:

* \* Currently receiving active cancer-directed therapy.

  * Unable to read or fluently speak English.
  * Determined by clinical staff to have preexisting or cancer-associated cognitive impairment that could interfere with study participation.
  * Acutely suicidal (e.g. intent or plan) or, with unstable medical or psychiatric condition verified by licensed study staff.
  * Characteristics related to inability to complete the study protocol.