This paper reviews current known issues in student self-assessment (SSA) and identifies five topics that need further research: (1) SSA typologies, (2) accuracy, (3) role of expertise, (4) SSA and teacher/curricular expectations, and (5) effects of SSA for different students. Five SSA typologies were identified showing that there are different conceptions on the SSA components but the field still uses SSA quite uniformly. A significant amount of research has been devoted to SSA accuracy, and there is a great deal we know about it. Factors that influence accuracy and implications for teaching are examined, with consideration that students' expertise on the task at hand might be an important prerequisite for accurate self-assessment. Additionally, the idea that SSA should also consider the students' expectations about their learning is reflected upon. Finally, we explored how SSA works for different types of students and the challenges of helping lower performers. This paper sheds light on SSA research needs to address the known unknowns in this field. Student self-assessment (SSA) most generally involves a wide variety of mechanisms and techniques through which students describe (i.e., assess) and possibly assign merit or worth to (i.e., evaluate) the qualities of their own learning processes and products. This involves retrospective monitoring of previous performance (Baars et al. 2014) and reporting, hopefully truthfully, the quality of work completed. The purpose of this manuscript is to review what it is known and unknown about student self-assessment (SSA) after decades of research and, based on such evidence, highlight plausible lines of research that could make better known what we currently know is unknown. SSA has been extensively and vigorously recommended as an appropriate approach to student involvement in formative assessment, wherever the Bassessment for learning^reform agenda has been advocated (Berry 2011; Black and Wiliam 1998). Hence, it is important for education that we have a clearer understanding of SSA.While the field of empirical studies into SSA is increasing, it seemed timely to review what has been established in SSA since so many studies seem to only be replicating, in new contexts, what we already know about SSA. Hence, the purpose of this paper is to expand upon these known and unknown issues and consider plausible directions for future research. We consider that the known unknowns, which will be established in this review, are so substantial that our recommendations are unlikely to be a roadmap with clear signposts and indicators of progress. Rather, we consider that this paper functions more as a series of lighthouses highlighting well-trodden rocky shores and pointing out more profitable directions in which SSA research should head.SSA is an important skill for at least four reasons. First, students who are trained in SSA have shown an increase in their learning and academic performance Panadero et al. 2012;Ramdass and Zimmerman 2008). Additionally, accuracy (i.e., reliable and val...