Although mentoring can have powerful benefits for youth, it can be a challenging responsibility for mentors. The literature emphasizes training and support as being essential for effective mentoring, but empirical research has not yet provided a psychometrically sound measure to assess this construct. The present study focuses on the development and initial evaluation of the Mentors’ Perceived Program Support Scale (MPPSS), an 11‐item inventory that addresses 4 areas of support: emotional, informational, tangible assistance, and appraisal. The MPPSS was administered to 664 mentors from 19 formal mentoring programs. Data analysis included a factor analysis, item response theory analysis, and an assessment of convergent and discriminant validity. Reliability and validity estimates of the MPPSS indicated that the MPPSS may have several advantages over the Match Characteristics Questionnaire's Programmatic Support subscale, one of the few available measures of mentor support. Implications for the use and further evaluation of the MPPSS are discussed.