In a world faced with ever-growing crises of climate change, economic inequality, and social injustice, sustainability has become a catch-all term to address these challenges and more. However, efforts to measure the social, environmental, and economic factors of sustainability are undermined by inconsistent understandings of the term. This research seeks to address this gap in sustainability research by constructing a wide-reaching propensity instrument that incorporates the different constructs of sustainability. A literature review informed propensity instrument construction. The first version of the instrument included 269 items, which were narrowed to 100 after an iterative process of merging, refinement, and elimination. The 100 scale items were deployed through an online survey, where 162 responses were collected to inform data analysis. Principal component analysis revealed two primary factors of Sustainable Behavior and Sustainability Attitude. After further refinement based on items’ factor-loading scores and communalities, 13 items remained that described sustainability as environmentally and socially conscious behaviors and attitudes. The third construct of sustainability, economics, was not present after such refinements, suggesting that purely economic behaviors and attitudes are disparate from individuals’ sustainability propensity. This new propensity instrument informs the understanding of sustainability and provides a tool for measuring sustainability with more breadth.