In this article, we evaluate the factor structure of the Multigroup Ethnic Identity Measure (MEIM; Phinney, 1992) and test whether the MEIM exhibits measurement invariance across ethnic groups taken from a diverse sample of students from 30 different colleges and universities across the United States (N = 9,625). Initial analyses suggested that a bifactor model was an adequate representation of the structure of the MEIM. This model was then used in subsequent invariance tests. Results suggested that the MEIM displayed configural and metric invariance across 5 diverse ethnic groups (i.e., White, Black, Hispanic, East Asian, and South Asian). There were indications that the MEIM displayed a similar factor structure with roughly equivalent factor loadings across diverse ethnic groups. However, there was little evidence of scalar invariance across these groups, suggesting that mean-level comparisons of MEIM scores across ethnic groups should be interpreted with caution. The implications of these findings for the interpretation and use of this popular measure of ethnic identity are discussed.