Conceptual discussions of sustainability emphasize the interdependent relationship between relevant social and environmental factors. Yet, traditional quantitative analyses of the topic have tended to estimate the exogenous or direct/indirect effects a predictor variable has on a particular measure of sustainability. We examine the endogenous, interdependent relationship between the three E’s of sustainability (economy, equity, and ecology), incorporating country-level data for 1990 through 2015 into cross-lagged structural equation models with reciprocal and fixed effects. Results from these longitudinal models suggest that over time, at the country level, increasing economic inequality reduces renewable energy consumption, with no evidence of reciprocal feedback. Keeping in mind the limitations of the analysis, we tentatively argue that the modern form of development has constrained the potential for the sustainability goals to feed back into each other.