The development of mathematical literacy in schools is of significant concern at the policy level, and research is an important source of information in this process. This review article focuses on areas of research interest identified in empirical projects on mathematical literacy, and how mathematical literacy in schools is approached by research. The following three main challenges are identified: both researchers and teachers are uncertain about how to develop students' mathematical literacy, specific attempts to work directly with mathematical literacy through mathematics alone have not been successful, and teaching for mathematical literacy appears to require non-traditional methods for teaching mathematics. More qualitative research is called for, with emphasis, for example, on classroom studies focusing on teachers' priorities regarding mathematical literacy, best-practice examples, or interventions in which teachers and researchers work together.