This paper introduces the philosophy of Grace Andrus de Laguna in order to renew interest in it. I show that, in the 1910s and 1920s, she develops ideas and arguments that are also found playing key roles in the development of analytic philosophy decades later. Further, I describe her sympathetic, but acute, criticism of pragmatism and Heideggerian ontology, and situate her work in the tradition of American, speculative philosophy. Before 1920, we will see, de Laguna appeals to multiple realizability to undermine reductionism in science, to support perspectival, scientific realism and, with help from a private language argument, to favour the view that mental states are classified by behavioural, teleological roles over what came to be called ‘type physicalism’. Her view of speech, mostly developed in the 1920s, tells us that its primary role is coordinating group behaviour rather than expressing thoughts. Belief is understood in terms of its causal role, including its causal relations to other kinds of mental states, when coordinating group behaviour. Thought is similarly understood. In developing her theory of mind, de Laguna rejects the pragmatist claims that belief can be reduced to dispositions to behaviour and that thought’s function is to address specific, rather than general, problems. She also favours meaning holism and rejects the analytic-synthetic distinction. In later work, de Laguna argues that individuals’ activity of self-maintenance brings universals, conceived of as irreducible potentialities, into being and makes them increasingly determinate. Further, she identifies the existence of all individuals with forms of self-maintenance and takes the existence of people to include maintenance of the cultural world. Such a unified treatment of existence, she holds, permits making its evolution intelligible. Heidegger’s view of being is rejected for not permitting this. All de Laguna’s work, we will see, fits a vision of philosophy as the systematic, imaginative and naturalistic examination of being as well as a source of criticism of science.