Chemical engineering design is in a constant state of flux. From advances in the practice of separation operations in chemical engineering to corresponding changes in the curriculum, much has happened in the seven years since the publication of Seader and Henley’s first edition of Separation Process Principles, including: (1) advances in the fundamentals of mass, heat, and momentum transport, (2) wide availability of computer programs to facilitate the application of mathematical models to a wide range of separation operations, (3) increasing interest in separations involving the solid phase, and (4) changes in the practice of chemical engineering to emphasize product design as well as process design.