Radical constructivists appeal to self-legislation in arguing that rational agents are the ultimate sources of normative authority over themselves. I chart the roots of radical constructivism and argue that its two leading Kantian proponents are unable to defend an account of self-legislation as the fundamental source of practical normativity without this legislation collapsing into a fatal arbitrariness. Christine Korsgaard cannot adequately justify the critical resources which agents use to navigate their practical identities. This leaves her account riven between rigorism and (...) voluntarism, such that it will not escape a paradox that arises when self-legislation is unable to appeal to external normative standards. Onora O'Neill anchors self-legislation more firmly to the self-disciplining structures of reason itself. However, she ultimately fails to defend sufficiently unconditional practical norms which could guide legislation. These endemic problems with radical constructivist models of self-legislation prompt a reconstruction of a neglected realist self-legislative tradition which is exemplified by Christian Wolff. In outlining a rationalist and realist account of self-legislation, I argue that it can also make sense of our ability to overcome anomie and deference in practical action. Thus, I claim that we need not make laws but can make them our own. (shrink)