The "Big Four" engineering fields consist of civil, mechanical, electrical, and chemical engineers. Of these, chemical engineers are numerically the smallest group. However, this relatively small group holds a very prominent position in many industries, and chemical engineers are, on average, the highest paid of the "Big Four". Additionally, many chemical engineers have found their way into upper management. A chemical engineer is either currently, or has previously, occupied the CEO position for : 3M, Du Pont, General Electric, Union Carbide, Dow Chemical, Exxon, BASF, Gulf Oil, Texaco, and B.F. Goodrich. Even a former director of the CIA, John M. Deutch, was a chemical engineer by training.

More typically, chemical engineers concern themselves with the chemical processes that turn raw materials into valuable products. The necessary skills encompass all aspects of design, testing, scale-up, operation, control and optimization, and require a detailed understanding of the various "unit operations", such as distillation, mixing, and biological processes, which make these conversions possible. Chemical engineering science utilizes mass, momentum, and energy transfer along with thermodynamics and chemical kinetics to analyze and improve on these "unit operations."