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.