Individual Placement and Support (IPS), an evidence-based supported employment model for working-age adults with serious mental illness, also serves transition age adults (TAY; ages 16-24). The IPS-Y is a new IPS fidelity scale tailored to this younger population. Although adopted worldwide, it lacks research on the psychometric properties of its two components (employment and education). Six IPS programs serving TAY were assessed on IPS-Y (Employment) in an initial review (Time 1) and on both components in a second review one year later (Time 2). We examined scale calibration, reliability, and validity for the IPS-Y in this sample. Fidelity reviewers use the full range of ratings, from "not IPS" to "exemplary," on both IPS-Y components. On the employment component, item calibration was excellent; internal consistency reliability was good at Time 1 (r = 0.81) and test-retest reliability was fair (r = 0.63). The IPS-Y (Employment) showed excellent sensitivity to change, with the mean scale score increasing from 88.3 to 105.5. IPS-Y (Employment) item ratings at Time 2 were similar to corresponding items in a sample of conventional IPS programs using the standard IPS fidelity scale. Predictive validity was promising for both components, with fidelity scale ratings positively correlated with site-level competitive employment rates (r = 0.57) and education enrollment rates (r = 0.69). IPS can be implemented to good fidelity for programs serving TAY. Preliminary findings regarding the psychometric properties of the IPS-Y Employment are encouraging, but replication in larger samples is needed.