Concurrent Validity Study Procedures. Assessment of pain experience will be obtained for study participants undergoing routine venipuncture as part of their clinic visit co-occurring with study entry and study completion. Observational, physiological response, parent-report, and self-report of pain experience will be obtained to provide convergent validity for measures of pain report. A brief measure of medical coping style, the Child Approach-Avoidance Rating Scale (CAARS; Appendix J) will be included to assess for shifts in coping strategies employed by the participant during painful procedures. Participants and parents will report on child pain experience before, during, and after the routine venipuncture that is part of their clinic visit on the day of initial contact. Participant response to routine venipuncture will also be captured via video recording to allow for an in-depth analysis of observable pain behaviors. Pre-procedural heart rate will be taken at three intervals: when the patient is first seen for the clinic visit, immediately prior to the venipuncture, and immediately following the venipuncture. Additionally, small extra vial of blood will be obtained (5mL) to measure the participant's level of endothelin-1, a biological marker of pain. This extra vial of blood will not require an additional needle stick. Finally, the medical records of all participants will be reviewed to obtain information about disease course.