The EROS computer code is described as a verified program for operational safety reactor events in the normal operating or mild upset range of Experimental Breeder Reactor II (EBR-II). Following a description of EROS, several cases of verification of experimental events with the code are presented. The code is found to adequately represent reactivity perturbations in EBR-II including operational rod drops, control rod drops, and oscillator experiments. In addition, the code will interpret flow-coastdown (loss-of-pumping-power) events with great accuracy.