Especially in North America, the house building industry has been misunderstood. Between the 1920s and the early 1970s, it underwent evolutionary change, but was always dominated by subcontracting and small builders, who relied on suppliers for credit and timely deliveries. Most observers damned it for inefficiency, and for not conforming to a corporate ideal of factory mass production, exemplified by autos and, later, aerospace. Some liberals sought to stabilise demand to enable larger scale and more efficient operations. A few academics claimed the industry had responded effectively to its business environment. Industry spokesman defended themselves, but few listened. Historical scholars have not probed behind the contemporary screen of criticism. To do so we should combine the findings of recent researchers who have shown that house builders are flexibly efficient with the arguments of historians of the 'other side' of industrialisation. Instead of learning from the factory model, the building industry can teach us about the trade-offs between efficiency and flexibility.