A clear relationship exists between the consistent selection and implementation of cognitively demanding tasks and students' conceptual understanding of mathematics. However, mathematics teachers often struggle to maintain the cognitive demand of implemented tasks, with a number of factors identified as contributing to this decline. As many students have limited opportunity to engage with cognitively demanding tasks, the percentage of students proficient in mathematics remains low and unchanged. Given that the consistent opportunity to engage with cognitively demanding tasks is key to increasing the percentage of students proficient in mathematics, understanding the role of tasks in the mathematics classroom is of essence to both mathematics students and the field of mathematics education. As such, the purpose of this paper is to describe the role of cognitively demanding tasks in the mathematics classroom, the barriers to task implementation, and the supports for students and teachers related to either their engagement with or implementation of cognitively demanding tasks.