Intangible capital which relies on essential human inputs, or "organization capital," presents a unique challenge for measurement. Organization capital cannot be fully owned by firms' financiers, because it is partly embodied in key labor inputs. Instead, cash flows must be shared with key talent and thus neither book nor market values will fully capture its value. Measurement of organization capital requires a model featuring these unique property rights. We use accounting data along with a simple example of such a model to measure the fraction of the US capital stock which is missing from book and market values.