Mr. Hanretty replaces Anne Campbell, who in January will become San Mateo County superintendent of schools after an uncontested election in June.
The appointment was made as part of the school board's recent reorganization of the district's management structure, according to a press release from the district, which oversees two schools: Corte Madera and Ormondale.
Corte Madera School Principal Carol Piraino is also making a move up in the district: She has been appointed assistant superintendent for special education and curriculum, the press release said.
Mr. Hanretty said Corte Madera will open the school year with "an experienced interim principal in place," but that "hiring a highly qualified individual to serve as the permanent principal at (the school) will be my top priority."
Mr. Hanretty received a bachelor's degree in public administration from the University of San Francisco, and has completed graduate work in finance, human resource and organizational development at the University of California at Berkeley.
He joined the Portola Valley district in 1999, and led school construction and renovation projects at Corte Madera, Ormondale, and Woodside schools.
Mr. Hanretty said the decade-long joint powers agreement between the Portola Valley and Woodside districts that allowed the sharing of his services as finance director ended last month.
Woodside has hired a new full-time chief business official, Robin Wasco, who worked previously in the South San Francisco School District, he said.
In a prepared statement, current Superintendent Anne Campbell said: "I can't think of two better people to lead the (district). Mr. Hanretty and Dr. Piraino bring a wealth of talent to their new positions.
"Tim is a true expert in the realm of school finance and the development of creative solutions to perplexing problems. ... Carol is a highly skilled educator who holds a profound vision for what schools can be in the 21st century and who possesses the management skills needed to make that vision a reality."