Authors conceptualize the notion of reflection as a higher psychological function from the perspective of cultural-historical psychology of Lev Vygotsky and discuss the development of teachers' reflective practice in the process of mastering and creating mediational means of reflective practice. In the current research literature the terms mediational means and "psychological tools" are often used interchangeably. On the grounds of the findings from the studies of teachers' reflection, conducted in Ireland, United States, and Russia, the authors distinguish mediational means from psychological tools, discuss their heterogeneity, and explore how the choice of mediational means transforms the process of reflective practice. Authors argue that teachers need to be educated to master meditational means of reflection to build their reflective practice and develop reflection as a higher psychological function.