Some commentators have attributed constructivism to Kant at the first-order level; others cast him as a meta-ethical constructivist. Among meta-ethical constructivist interpretations I distinguish between ‘atheistic’ and ‘agnostic’ versions regarding the existence of an independent moral order. Even though these two versions are incompatible, each is linked with central Kantian doctrines, revealing a tension within Kant's own view. Moreover, among interpretations that cast Kant as rejecting substantive realism but embracing procedural realism, some (i.e., those that are ‘constructivist’) face charges of indeterminacy or relativism, while others (practical reasoning views) face ‘daunting rationalism’ objections. I close with some objections to interpreting Kant as a meta-ethical constructivist.