I study the optimal integration of humans and technologies in multi-layered decision-making processes. Each layer corrects errors made by previous layers but also introduces new errors. The ratio between these two aspects serves as a one-dimensional quality measure that uniformly ranks all technologies. Optimal integration requires higher quality technologies to be applied later. Furthermore, technologies asymmetrically influence human effort. Initial players specialize in correcting errors, while final players focus on avoiding new errors. When error costs depend on unobservable states, a uniform ranking is not generally possible. Consequently, the introduction of new technologies can significantly disrupt the integration of existing ones.