The study attempts to examine the economic, demographic, and development determinants of economic complexity by using annual data spanningfrom 1995 to 2019. The advanced panel quantile method is employed toestimate the long-run impacts of driving forces on economic complexityalong with its distribution. The empirical results reveal several importantpoints. First, income, population density, human capital, and governmentconsumption appear to improve economic complexity while natural resources rent imposes a negative effect. Second, the impacts of such factors are heterogeneous across quantiles of economic complexity. Third,there exist huge differences in the roles of such factors between high-income and middle- and low-income countries. Based on findings, applicablepolicies are provided.