Recent years have seen a surge in research comparing bilinguals to monolinguals, yet synthesizing this literature is complicated by the diversity of language and social backgrounds behind these dichotomous labels. The current study examines the labels and descriptions reported in 186 studies comparing bilinguals and monolinguals published between 2005–2015 in order to understand how bilingualism has been operationalized and to describe the degree to which different facets of bilingual experience are reported. Proficiency and usage were the most frequently reported features (77% and 79%), followed by language history (67%) and the language of schooling (60%). However, less than half of the studies measured proficiency objectively or reported proportional usage, and even less – 30% – described the sociolinguistic context from which the sample was drawn. Given the increase in language contact due to globalization, more transparent and comprehensive reporting of participant characteristics is critical to building our understanding of how bilingualism affects experience.