Serving Arizona for over 25 years, Educational Services (ESI) is focused on helping solve the staffing crisis for public school districts, governments, and colleges. Our mission: "With integrity and heart, we support and serve those who educate and serve our community." ESI's featured services include a return-to-work program known as RetireRehire, and SubSource, the largest substitute staffing program in the state. ESI has proudly served over 13,000 of Arizona's public retirees and actively employs over 7,000 substitute educators.