9- week health behavior promotion group intervention

The proposed intervention will include eight modules across nine weekly group sessions targeting psychoeducation of CHR-P symptoms, goal setting, physical activity, sleep, substance use, nutrition, and evidence-based strategies for stress management. Intervention facilitators will utilize motivational interviewing (MI; Miller & Rollnick, 2012) strategies to engage youth in goal setting to target change in health promotion behaviors. Caregivers will be invited to join at the end of each session for a 10-minute check-out where an outline of content covered and patient goals for the week will be shared.

Feasibility will be measured by recruitment (participants approached/ participants enrolled) and retention (participants enrolled/ participants completed at least two-thirds of the intervention). Feasibility data will be summarized by the percent recruited, the percent retained by group and the mean and median number of sessions attended by group. The percent who attended each session by group over time will also be reported. Good feasibility will be defined as 70% of those enrolled completing at least two-thirds of the intervention (6 sessions).

The mean profile from baseline to post-treatment for physical activity as assessed by the International Physical Activity Questionnaire - Short Form (IPAQ-SF; Craig et al., 2017). Activity levels will be self-report.

Sleep will be assessed via self-report on the PROMIS Pediatric Sleep Disturbance scale (Buysse, et al., 2010). The Pediatric Sleep Disturbance Scale consists of 15 items rated 1 = Never, 2 = Almost Never, 3 = Sometimes, 4 = Almost Always, and 5 = Always, with a higher score indicating more sleep disturbance.

Participant subjective stress will be assessed via the 10-item self-report Perceived Stress Scale ( PSS; Cohen et al., 1983).The PSS consists of 10 items rated 0= Never to 4= Very Often, with a higher score suggesting more stress.

Alcohol and drug use will be measured by clinician rated on the Alcohol Use Scale and Drug Use Scale (AUS/DUS; Drake et al., 1996). This measure rates frequency and impairment associated with alcohol and drug use. Alcohol and drug use are rated on both frequency (0= no use to 5= almost daily) and impairment (0= abstinent to 5= dependence with institutionalization). A rating of 3 or higher on impairment corresponds with substance use disorder.

The social validity of the intervention will be described qualitatively using a modified version of the Semi-Structured Interview for Social Validation. This interview measure includes questions directed at assessing the significance of the goals of the intervention, the acceptability of the procedures used, and the importance of the effects of the intervention. A thematic analysis procedure will be utilized for qualitative analysis of the interviews.