Chapter 2 highlights the use and effects of Solow’s model as an instrument of measurement. It relates the model to the postwar politics of growth and productivity and a line of inquiry that sought to gauge the national whole in terms of monetary units. Existing measurement practices at the National Bureau of Economic Research (NBER) involved the activities of collecting, compiling, and processing data; its researchers complemented and qualified their numbers with descriptive, verbal accounts about how the data had been made and how different measurement procedures led to different results. Here, the model reordered knowledge and nonknowledge about productivity. While commentators were shocked by its utter constructivism and disregard for the ways data were made, it offered a seemingly clean-cut method of measurement that turned statistical inference into a technical procedure. Whatever the model’s neoclassical reading of numbers did not account for was efficiently stashed away in a residual term labeled “technical change.” While Solow explicitly noted that the rest captured all kinds of (relevant) things, the technique remained and was soon denoted “the Solow residual.”