Foundational Domains identifies the generative architecture shared by every domain of reality that exhibits structure, coherence, and change. Rather than treating physics, biology, cognition, society, morality, and theology as separate kinds of things, the paper shows that each domain expresses the same minimal operators: constraint, orientation, and time. Constraint provides the structural geometry of the domain; orientation is the system’s state relative to that geometry; and time is the continuity of orientation under constraint. These operators are not analogies across fields but the necessary conditions for coherent transformation in any system.To explain how domains form and maintain coherence at scale, the paper introduces the Domains Triad—Structure, Dynamics, Identity. Structure defines the domain’s boundary and affordances; dynamics describe the lawful ways orientation propagates within that structure; and identity captures the coherence that persists across change. This triad accounts for why domains differ, how they stabilize, and how they remain intelligible as they evolve.By articulating the generative invariants shared across physics, life, mind, society, morality, and theology, Foundational Domains provides a domain‑neutral framework for understanding how reality organizes itself into stable, differentiated regions. The result is a unified architecture that clarifies both the unity and the diversity of the major domains of inquiry.