In a letter to board members today, Palo Alto Unified School District Superintendent Mary Frances Callan announced her retirement effective on Aug. 30, 2007.

After working 41 years in educational services, and five years as superintendent in Palo Alto, Callan said she is proud of the work the district has done under her leadership. Callan began her letter explaining that she was only committed to a five-year tenure with the district, and she realized she is nearing the end of her tenure.

"As fond as I am of meeting deadlines, I was fonder still of this wonderful school district, its students, its staff, and the many, many volunteers who have worked so tirelessly on its behalf," Callan wrote.

Callan will continue her work until next August with finishing the attendance area review, Mandarin immersion feasibility study, and district priorities.

Over the course of her time, she led the school board to revise staff policies, to manage a $6 million reduction in funds, and to progress in standardized test scores.

"I appreciate the opportunity I had to lead the district team in calm times and stormy ones as all of us strived for what was best for our students," Callan wrote. "I want to thank you again for the opportunity to lead the very best school district in the country."

Callan announced her retirement early to allow the board time to conduct a national search for a new superintendent.