Aims and objectives: Proficiency assessment is a key methodological consideration in the field of bilingualism, and previous reviews have highlighted significant variability in both the use and type of assessment methods. Yet, previous reviews of proficiency assessment methods in bilingualism have failed to consider key study characteristics (e.g., methodology and subfield) that may impact the choice of proficiency assessment method. This paper provides an updated systematic review of proficiency assessment methods in the field of bilingualism, analyzing trends within different methodological approaches and linguistic subfields. Design/methodology/approach: A systematic review was conducted, examining recent research articles in the field of bilingualism, broadly defined. A total of 17 journals (of 100) and 140 empirical research articles (of 478) with bilingual participants fit the relevant inclusionary criteria. Data and analysis: Studies were coded for several characteristics, including methodology (e.g., quantitative vs qualitative), linguistic subfield (e.g., psycholinguistics), and the method of proficiency assessment (e.g., standardized testing, self-reporting). Findings/conclusions: Analyses revealed a number of different methods of proficiency assessment currently used in bilingualism research. However, different trends were found by methodology type and linguistic subfield. Broadly, the results revealed greater use of proficiency assessments in quantitative research than qualitative research. Moreover, while there was significant variability in all of the subfields examined, several within-subfield trends were identified. Originality: This study provides an update to previous findings, establishing current proficiency assessment practices in bilingualism research. In addition, acknowledging the unique needs of different types of research, this study is the first to examine trends within different methodological approaches (i.e., quantitative vs qualitative) and subfields of bilingualism (e.g., psycholinguistics, sociolinguistics). Significance/implications: The notable variability in proficiency assessment methods within different subfields suggests a greater need for subfield-specific norms to facilitate comparative analysis. Several key considerations are given for the selection of proficiency assessment methods in bilingualism research.