With the merge of mobile computing and electronic commerce technologies, millions of mobile users in the near future could carry a mobile device requesting services through the electronic commerce applications. While serving such a mobile user, the server should consider how to minimize the response time of the request. This chapter discusses the issue of data processing for mobile commerce systems. Due to the characteristics of a mobile commerce environment such as user’s mobility, the user may not be at the same site as where he/she issued the request when the request’s result is ready to deliver to the user. This chapter argues that conventional strategies for query processing are no longer adequate in a mobile commerce environment and introduces some query processing strategies considering mobility for the mobile commerce systems. All the strategies are presented along with a cost analysis as the theoretical basis. Last, some of outstanding and interesting issues are described.