Since 2013 I’ve been writing a series of articles in my Insights column, in Supply Chain Management Review (SCMR) magazine, about e-tailing. It chronicles the evolution of e-commerce vendors—mostly aboutmarket-leader Amazon - as they’ve captured more of the retail business from the traditional brick-and-mortar retailers, largely market-leader Walmart. This column draws from the latest in the SCMR series because it focuses on ‘successful’ inventory management planning, buying, and fulfillment processes. In short, Amazon excels in operating a ‘responsive’ supply chain, while Walmart’s success is as an ‘efficient’ one. In both cases, their strengths become their weaknesses when competing for the other’s core business.