Alejandro Alvarez, who for the past three years has been associate superintendent for business services, has accepted a similar position with Compton Unified School District.
The departure was announced at Wednesday night's school board meeting.
Alvarez has worked at Fontana Unified for 17 years, starting his career as a kindergarten, first- and second-grade teacher. He later moved up to assistant principal and then principal.
Before his position in business services, Alvarez was director of certificated employees in the district's Human Resources department.
Board members and administrators praised his job performance as a key member of the district's cabinet and for his ability to present budgets and financing alternatives in easy-to-understand terms.
In an interview, Superintendent Cali Olsen-Binks said his position will likely be filled on an interim basis by a retiree to give the district more time to find a replacement.
Discussion on an adult bullying-prevention policy was tabled to give board members time to review a proposal "with teeth" that was presented by board member Kathy Binks.
Binks presented an alternative to the policy, which was drafted by the board's attorney and included in the packet of information board members receive before the meeting.
Binks proposed a resolution to control instances of bullying "by adults, including, but not limited to, governing board members, toward other adults, including other board members" calls for "governing board members found by a majority of the board ... to have violated this policy may be subject to appropriate legal action, public censure and public disclosure of the conduct found to be in violation of this policy."
Binks, who will retire from the board next month after 25 years, said she hopes other board members will pursue implementation of this policy.
Because voters approved Proposition 30, designed to raise money for schools and public-safety operations, the school board unanimously approved the reinstatement of five school days that had been trimmed for the 2012-13 school year in an effort to save slightly more than $7 million in utility and salary costs.
The reinstatement means that the school year will increase from 175 to 180 days. The additional days will be the week of March 25.