Understanding the determinants of sales success and sales failure has organization wide implications, ranging from an improved salesforce to improved corporate performance. However, a paucity of research on sales failure has resulted in an under-conceptualized field largely built on assumptions. This research proposes to overcome salesforce failure attribution biases by collecting data from the industrial buyer’s perspective. Thirty five post-mortem interviews with procurement decision makers from buying organizations were collected following a failed sales proposal. The context of these failed sales proposals was for multi-year industrial service key account contracts (>$5 Million). The result of this naturalistic inquiry is a model which outlines the determinant attributes of sales failure: price, adaptability and relationship-potential. An experimental design was conducted following this exploratory research in order to test the derived drivers of sales failure and success, as well as provide a trade-off analysis of the three emergent sales proposal themes. Results indicate that a lack of adaptability has the strongest impact on the sales failure outcome variable, as well as buyer characteristics have a potentially moderating impact on the relative trade-off weights between price/adaptability and price/relationship-potential.