Integrating literacy in science and mathematics learning and teaching has been an ongoing endeavour. There are frameworks developed to guide teachers' practices, but little is reported on assessing literacy simultaneously with scientific or mathematical content knowledge. We reviewed the literature on assessing literacy in science and mathematics to develop a coherent knowledge base using the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA). We accessed 683 peer-reviewed publications from three databases, and upon application of exclusion criteria, only 13 articles remained for full analysis. We report the macro skills focused, assessment tools and strategies used, and reported outcomes. We also discuss the geographical, practical, and theoretical gaps and highlight critical areas for future investigations.