The purpose of this study was to evaluate a recently developed classroom collective moral disengagement scale (CMD). The 18-item scale was evaluated on a sample of 1626 fourth grade students in Sweden. Through confirmatory factor analysis, the unidimensional structure of the scale was verified, and the internal consistency was good. The scale is related to individual moral disengagement and to bullying behavior both on an individual level, which supports the criteria validity of the scale and on class level, which supports the construct validity of the scale. Multigroup analyses demonstrated measurement invariance across gender. These results indicate that the scale can be used in studies on CMD, and girls’ and boys’ mean scores may be compared.