The present work outlines a logical and philosophical conception of propositions in relation to a group of puzzles that arise by quantifying over them: the Russell-Myhill paradox, the intensional Liar paradox, and Prior's Theorem. First, I motivate an interpretation of the Russell-Myhill paradox as depending on the notion of aboutness. Aboutness informs the notion of propositional identity, of which I will offer two formalizations, depending on choices that have to be made about the syntax of propositional variables. I then extend to propositions a predicative response to the paradoxes presented in Linnebo (2013, 2018). On this approach, modal operators are used to uncover the implicit relation of dependence that characterizes propositions that are about propositions, which Russell-Myhill shows to have logical significance. Thus, the justification for predicativity is found in two ideas: (i) propositions are, in some sense, language-dependent entities; (ii) there is a distinction between what a sentence says (its semantic value) and what it expresses (a proposition). The propositions that can be expressed outstrip those that are, so to speak, "available'' for reference and quantification. A modal abstraction principle for propositions formalizes this conception, and its benefits are shown by application to other intensional puzzles. The resulting view is an alternative to the plenitudinous metaphysics of unconstrained comprehension principles defended by Williamson (2013), and Bacon et al. (2016), among others.