Introduced nearly 25 years ago, the paradigm of mass customization (MC) has largely not lived up to its promise. Despite great strides in information technology, engineering design practice, and manufacturing production, the necessary process innovations that can produce products and systems with sufficient customization and economic efficiency have yet to be found in wide application. In this paper, the state-of-the-art in MC is explored in order to answer the question of “why not?” and to highlight areas for specific research in the MC paradigm. To establish perspective for this work, we consider MC to be a product development approach which allows for the production of goods — after a customer places an order — which minimize the tradeoff between the ideal product and the available product by fulfilling the needs and preferences of individuals functionally, emotionally and anthropologically. Results of this research were generated by reviewing 88 papers from various journals that span three domains of interest (marketing, engineering, and distribution) and explore proposed methodologies, specific information inputs and outputs, proposed metrics, and barriers toward the implementation of MC. Qualitatively, we show that the lack of MC in application is due to two factors: 1) a lack of marketing tools capable of capturing individual needs that can be mapped to the technical space; and 2) a lack of information relation mechanisms that connect the domains of marketing, engineering, and distribution. In the end it is our belief that MC is realizable and that eventually it will emerge as a dominant paradigm in the design and delivery of products and systems. However, pursuing the opportunities for research presented in this work will hopefully speed this emergence.