Abstract
This developmental paper examines the extent to which smart cities are sustainable by integrating sufficiency and necessity perspectives. Using data from 639 Brazilian municipalities in 2024, the analysis combines linear regression and Necessary Condition Analysis (NCA) to assess the relationship between ten smart city dimensions and municipal performance on the Sustainable Development Goals (SDGs). Regression results indicate that environmental performance, education, health, technology and innovation, and, marginally, urbanism, positively influence sustainability outcomes, increasing the model’s explanatory power by 21.9 percentage points beyond territorial and demographic controls. However, NCA reveals that several dimensions, particularly urbanism, health, education, environment, and governance, operate as necessary conditions, establishing minimum thresholds for high SDG performance. The findings suggest that sustainability in smart cities is conditional and structurally bounded: technological advancement enhances sustainability only when embedded within robust social, environmental, and institutional foundations, challenging technologically deterministic interpretations of the smart city paradigm.