Cognates are studied in many psychological studies of bilingual language processing. Despite their frequent use, there is no clear operationalized definition of what constitutes a cognate. We conducted a literature search in three major journals to better understand how cognate status is typically defined and operationalized. In these journals, we analyzed similarity of cognate and non-cognate stimuli. We found that approximately 60% of the reviewed studies operationalized cognate status empirically. Stimulus analyses revealed a similarity continuum between cognates and non-cognates without a consistent cut-off. Based on these results, we make recommendations for future research.