. The emergence of information and communication technologies infrastructure has transformed the global economy. The development of information technology infrastructure is lim- ited to some developed countries though. This research explores the role of information technology infrastructure in B2C e-commerce growth at the country-level from the perspective of growth theory in economics. We propose a hybrid exogenous and endogenous growth model to explain e-commerce growth. We estimate a panel data model that incorporates the direct effects of e-commerce infrastructure and other key explanatory variables. We further specify a simultaneous effects model that permits the anal- ysis of reverse causality in the association between e-commerce growth and Internet-based selling technology adoption. The data include 24 countries in four different regions around the world. We found that endogenous factors (online payment availability, and Internet-based selling technology adoption) and exogenous factors (international openness) both contribute to B2C e-commerce growth in a country. We also found that there is a two-way interac- tion between Internet-based selling technology adoption and e-commerce growth. The empirical findings support the effective- ness of our theoretical approach. Keywords: Cross-national study, e-commerce, endogenous growth, exogenous growth, Internet, technology adoption. ______________________________________________