Given that smartphones are widely used as a key means for m-commerce, this study aims to provide in-depth understanding of smartphone-based m-commerce use. Drawing on TAM, we develop the basic framework of our research model with the three constructs namely, usefulness, ease of use, and m-commerce use. TAM has parsimony, robustness, and generalizability so that it can be widely applied to predict user behavior regardless of particular IT. However, due to these strengths, TAM cannot capture unique characteristics embedded in particular IT. Therefore, this study attempts to expand TAM by including mobile-specific characteristics (i.e., service ubiquity and LBS) and a SST (self-service technology) characteristic (i.e., user control). A total of 164 responses were collected on users having experience in m-commerce. The key findings are as follows: first, the results indicate that TAM is a very useful theoretical lens to predict user behavior in the context of m-commerce enabled by smartphones. Second, the results show that service ubiquity and LBS lead to increased usefulness of m-commerce. Finally, the results demonstrate that user control is positively associated with both usefulness and ease of use. Discussion and implications on the findings are provided.