The present study reports on an investigation of the generalizability of the technical adequacy of the Positive Experience at School Scale (PEASS) with a sample of students (N = 1,002) who differed substantially in age/grade level (i.e., adolescents in middle school as opposed to children in elementary school) and ethnic identity (i.e., majority Black/African American as opposed to majority Latino/a) in comparison with the measure’s primary development sample. Findings from confirmatory factor analyses indicated the original latent structure of the PEASS was tenable in the current sample and that the measure was invariant across gender and grade level, with some small demographic differences identified via latent means testing. Additional psychometric findings regarding the technical adequacy of the PEASS with this sample, including its observed scale characteristics and simulated classification utility with criterion measures of academic self-efficacy and school connectedness, are also presented. Implications for future research and practice are discussed.