Our focus herein is on developing an effective taxonomy for the simultaneous and real-time management of supply and demand chains. More specifically, the taxonomy is developed in terms of its underpinning components and its research foci. Interestingly, our taxonomic approach highlights a very critical research area at which both supply and demand are flexible, thus manageable. Simultaneous management of supply and demand chains sets the stage for mass customization which is concerned with meeting the needs of an individualized customer market. Simultaneous and real-time management of supply and demand chains, in turn, set the stage for real-time mass customization. The benefits of real-time mass customization can not be over-stated as products and services become indistinguishable and are co-produced in real-time, resulting in an overwhelming competitive economic advantage.