Abstract Mentoring programs are a common positive youth development intervention that serve children of incarcerated parents (COIP). COIP are a particularly vulnerable population because they are exposed to a multitude of challenges, including family instability, stigmatization, and stress. A growing literature highlights the negative outcomes associated with being a COIP, including substance use in late childhood and early adolescence. Non-parental adult mentors can provide vital support to COIP. Limited research, however, has been conducted to explore characteristics of mentors that may make them more effective in mitigating negative outcomes and promoting positive outcomes in youth. With this R03, we aim to fill the gap in the available research by identifying characteristics of effective mentors working with vulnerable youth. We will leverage an existing, recently collected dataset of over 1,300 COIP, their mentors, and their parents or custodial caregivers from 20 mentoring programs across 15 states. The dataset represents a diverse population of vulnerable youth (mean age=11.2 years; SD=2.13 years) and includes background information about the caregiver’s incarceration. 50% of the sample were girls and approximately 53% were Black and 36% were White; 22% were Hispanic/Latinx. 24% had multiple caregivers who had been incarcerated. 46% had a caregiver who was currently incarcerated and the remaining 54% had a caregiver who had been previously incarcerated during the youth’s lifetime. The majority of the youth knew about their caregiver’s incarceration (85.55%) and 17% of the mentee sample had witnessed the arrest of their incarcerated caregiver. Before being matched with a COIP mentee, mentors completed a baseline assessment in which they reported whether or not they worked in a helping profession, whether they had any experience with incarceration or parental incarceration, their attitudes toward youth, empathy, volunteer role identity, and personality characteristics. We hypothesize that mentor characteristics will be associated with more positive youth outcomes (e.g., lower substance use, externalizing, internalizing problems) and match outcomes (e.g., length and quality of the mentoring relationship) for COIP. Several included mentor characteristics represented having a positive orientation towards working with youth such as being from a helping profession and having personal experience with incarceration (i.e., being a “credible messenger”). They involve high levels of empathy, as they entail working with others who might be vulnerable or greater awareness of issues related to caregiver incarceration. Analyses will be conducted using a series of multilevel moderated growth curves, multilevel logistic regressions, and survival analyses. The findings from this R03 will add to our knowledge base about the mentor characteristics that can improve the impact of this popular intervention for COIP. The ultimate goal of this work will be to help ...