The area under load versus load-line displacement record represents the sum of the stored potential energy, the released elastic energy, and the dissipated plastic energy necessary to grow a crack through a test specimen. When partitioned as presented in this paper, these energy components can be evaluated in terms of current elastic-plastic fracture parameters. The authors show that the elastic energy release rate, G, as calculated by measuring the appropriate component from the test record, is identical to G as calculated from Kg. The plastic energy dissipated, as measured directly from the load-displacement record, represents a much higher value than would be indicated by current J-type calculations. In all cases examined, it is further shown that energy released or dissipated is strongly dependent on the size of the test specimen and the size of the initial crack length. Further, while rolling orientation and prestraining of the steels investigated affect the plastic energy dissipation rate, there seems to be little effect on the elastic energy release rate.