This article reviews that almost every engineer is involved in some way in the planning of experiments, whether they are laboratory experiments, field tests, or computer simulations. A set of techniques called Design of Experiments (DOE) has proved to be an extremely useful methodology for enhancing the effectiveness of that planning. Six Sigma quality programs have been a mechanism for promulgating DOE in industry, but new research shows that a complementary approach, based on a set of adaptive one-factor-at-a-time experiments, leads to better results under many conditions. The full-factorial DOE method, which was initially developed to study agriculture, sets up an experiment for each possible combination of the factors that need to be tested. For example, consider the development of a new clutch. One aspect of its performance is drag torque—the amount of torque the clutch transmits when it is disengaged. A performance goal is to minimize drag torque by appropriate selection of materials, geometry, and other parameters. DOE is a remarkably successful procedure, which has had a profound influence on the professional practice of engineering.