Globalization, with its inherent cultural mixing, has made traditional measures of cultural identity based on language, religion or rituals, inappropriate for assessing cross-cultural composite identities in multicultural societies. Culturometrics, by contrast, considers cultural identity of individuals and sub-groups as a complex composite of primary cultural identities evidencing cultural influences from society's other cultural groups. It uses Cultural Indices, which are measures of privileged information statistically grounded in the consensual values of cultural sub-groups. Cultural Indices are more discriminating than traditional nominal categorizations of cultural identity. They allow quantitative comparisons between individuals and between cultural sub-groups, and can be used to predict comparative cultural behaviours. This paper demonstrates the construct validity and concurrent validity of the measurement method and reports on its use in studies of pre-determined ethnic identities in Fiji and socially determined cultural identities in Jamaica. The details provided allow replication as part of identity research in other culturally diverse contexts.