The Australian National University Centre for Resource and Environmental Studies Ecological Economics Program (EEP) was established in 1994 as part of the Institute of Advanced Studies Strategic Initiatives. EEP aims to promote ecological economics by conducting research and serving as a focal point for activities in the Canberra region. It hosts the ANZSEE office, runs seminars and a working paper series on the World Wide Web, and provides research supervision. The working paper series reports on research by academic staff, visitors, and students. The paper presents a multivariate cointegration analysis of the role of energy in the U.S. macroeconomy. It extends previous Granger causality analysis to test for cointegration between energy and GDP. The results show that cointegration exists, and energy input cannot be excluded from the cointegration space. The findings support the idea that energy Granger causes GDP, contradicting earlier bivariate models that suggested no cointegration between energy and output. The study uses a vector autoregression (VAR) model with GDP, energy use, capital, and labor inputs. Energy is measured using a quality-adjusted index. The analysis shows that energy is significant in explaining GDP and that there is cointegration in the relationship between GDP, capital, labor, and energy. The results support the idea of increasing returns to scale and provide evidence for basic macroeconomic "stylized facts" regarding business cycle propagation. The paper also discusses the implications of energy as a limiting factor in economic growth and the effects of energy supply shocks on output. The results are consistent with previous studies and support the idea that energy plays a significant role in economic growth. The analysis highlights the importance of multivariate approaches in uncovering causal relationships between energy and GDP.The Australian National University Centre for Resource and Environmental Studies Ecological Economics Program (EEP) was established in 1994 as part of the Institute of Advanced Studies Strategic Initiatives. EEP aims to promote ecological economics by conducting research and serving as a focal point for activities in the Canberra region. It hosts the ANZSEE office, runs seminars and a working paper series on the World Wide Web, and provides research supervision. The working paper series reports on research by academic staff, visitors, and students. The paper presents a multivariate cointegration analysis of the role of energy in the U.S. macroeconomy. It extends previous Granger causality analysis to test for cointegration between energy and GDP. The results show that cointegration exists, and energy input cannot be excluded from the cointegration space. The findings support the idea that energy Granger causes GDP, contradicting earlier bivariate models that suggested no cointegration between energy and output. The study uses a vector autoregression (VAR) model with GDP, energy use, capital, and labor inputs. Energy is measured using a quality-adjusted index. The analysis shows that energy is significant in explaining GDP and that there is cointegration in the relationship between GDP, capital, labor, and energy. The results support the idea of increasing returns to scale and provide evidence for basic macroeconomic "stylized facts" regarding business cycle propagation. The paper also discusses the implications of energy as a limiting factor in economic growth and the effects of energy supply shocks on output. The results are consistent with previous studies and support the idea that energy plays a significant role in economic growth. The analysis highlights the importance of multivariate approaches in uncovering causal relationships between energy and GDP.