Constructivism as a metanormative theory is a relatively recent development in philosophy, although its roots can be traced back to Kant. John Rawls brought constructivism onto the scene in the form of his political philosophy and some of these ideas were then developed by Thomas Scanlon in his normative theory. But it is probably not until Christine Korsgaard that we have an attempt to bring constructivism into the domain of metanormative theory. It has since become a hotly debated issue, with a lot of the discussion focusing on Korsgaard’s work. Recently, more constructivists have emerged with interesting takes on how to make constructivism a plausible metanormative theory, such as Aaron James and Sharon Street. Now that constructivism is firmly on the metanormative scene we can begin to unpick the main features of the theory and enquire as to how tenable it is.