This study investigates small and medium-sized enterprises' e-commerce adoption (e-CA) in Indonesia. This study differs from all the previous research on this topic, which was designed using linear models, since this study uses a structural data set and an equation model. It comprehensively outlines a new model with sequentially ordered readiness. Moreover, this research presents critical reasoning for this new model. This study rearranges organizational, industrial, and national readiness into a sequential model. The new model could explain and describe the small and medium-sized enterprises' e-CA better than all the previous research had done. It means that organizational, industrial, and national readiness influence their stages consecutively and result in e-CA. From a methodological perspective, industrial and national readiness work as intervening variables. This suggests that each readiness is not a mutually exclusive construct, but it relates to the others in the sequential order. Therefore, this study infers that national strategic policies to enhance the small and medium-sized enterprises' e-CA should be applied during the first, initial stage, starting from organizational to industrial and ending with national readiness. It also means that SMEs should construct their enterprises to be sequential and structural.