In the Introduction, we not that most groupings of theories into schools or frames are based on two variables: shared perspectives on organizations and the period in time during which the most important works were written. Thus, the giants of the neoclassical era include, for example, James March, Philip Selznick, and Herbert Simon. This does not mean, however, that their significance ended with their neoclassical era work. These three theorists in particular have continued to make major contributions into the turn of the century—contributions that have extened beyond the limits of both the neoclassical era and the perspective.