All ESEP candidates, regardless of their education or years of experience, are required to have references verify at least ten years of systems engineering experience. They do not have to verify all 20 or more years of required SE experience. This is different from CSEP applicants. There is no requirement that the references be from the most recent ten years of experience.

Another requirement for references that differs between CSEPs and ESEPs is that ESEP references do not have to confirm a particular depth and breadth of experience. 

Zero, one or two of the ESEP references may be interviewed over the phone as part of the ESEP assessment process. It is useful but not required to have at least two references who can speak to recent systems engineering leadership.