Public health discipline and practice have prioritized work on poverty and populations at high risk for material deprivation, with less consideration for the full spectrum of financial circumstances relative to well-being. Public health can make a much-needed contribution to this area, which is currently dominated by the financial industry, focused on individual behaviors, and lacking the definitional consensus needed for research and evaluation. A population-level lens can reveal the social determinants and health consequences of real or perceived poor financial circumstances. This article aims to improve conceptual understanding of financial circumstances among public health scholars and professionals. We identified concepts through a critical literature review of peer-reviewed and practice-based resources on financial well-being and financial strain. We developed a glossary of concepts related to financial circumstances and categorized concepts according to their level of influence using an approach informed by socioecological models. We provide a concept map that illustrates the relationships between concepts in the context of their levels of influence. This article will help to advance an agenda on financial well-being promotion in public health research and practice. (Am J Public Health. 2024;114(1):79-89. https://doi.org/10.2105/AJPH.2023.307449).