Metasemantics studies the foundations of meaning, asking what makes it the case that certain words have the meanings that they do. But what makes metasemantic theories true? This question has been all but ignored in philosophy of language. In this book, Cohnitz and Haukioja address this issue and argue that just as in metasemantics, both internalist and externalist answers are available for this foundational question. The authors introduce and defend meta-internalism, arguing that the foundations of reference and meaning are anchored in the individual dispositions and psychological states of language users, offering an alternative to meta-externalist views that would appeal to broader community-based or otherwise external factors. Meta-internalism is, moreover, compatible with semantic externalism as usually understood, and provides an explanation of why externalism is true. Through a critical examination of prominent theories and thought experiments, the book explores fundamental issues like reference failure, conceptual engineering, and the metaphysical implications of reference, as well as the methodology of theories of reference. With its focus on the foundations of metasemantics, the book provides a fresh and empirically informed perspective on one of the core questions in the philosophy of language. Foundations for Metasemantics is essential reading for philosophers, scholars, and students seeking to understand the underlying principles that support our theories of meaning and reference.