Abstract: All accelerator-based neutrino experiments depend heavily on event-generator Monte Carlo programs. These programs are closely matched to experimental needs, but contain an interesting mix of nuclear and high-energy physics theory. This talk will discuss the needs of experiments at Fermilab, where GENIE is the main software package. Applications of event-generator use by experiments show potentially new directions. The main part of the talk focuses on event-generator strategies, accomplishments, and new directions. GENIE provides most of the examples.