"It was hard for a while," when public distaste for female-only schooling caused enrollment to dip in the 1970s, said Pang, who authored the book, "Castilleja: Celebrating a Century."
Yet the school endured and this year has 415 girls from sixth through 12th grades enrolled. Its kick-off celebration is scheduled for 3 p.m., with festivities from carnival games to a Decade Parade of alumnae from different eras. There will even be a few men marching, since Castilleja used to have a co-ed primary school until the 1950s, Director of Communications Dana Sundblad said.
Nearly 300 alumni are expected to attend, and the party is geared primarily for members of the Castilleja community, she said.
The school's mission has remained true over the years. Founded in 1907 as a college preparatory for neighboring Stanford University, it continues to send 100 percent of graduates to four-year colleges, said Head of School Joan Lonergan.
But it hasn't always been easy. Founder Mary Lockey allowed poorer students to attend tuition-free during the Depression, a compassionate practice that led to bankruptcy by 1941. Teachers agreed to carry on without pay to help graduate that year's class, and the school became a nonprofit institution in the following year, according to the Web site.
The changing tide of public opinion also threatened all-girls education, Pang said.
The women's liberation movement of the 1960s and 1970s led many all-female schools to transition to co-education and Castilleja's enrollment dropped, Pang said. But when school director Don Westmoreland visited a school that had transitioned to co-ed in the early 1970s, he was unimpressed, Pang said.
"He visited the gym and asked about the women's basketball team. They said, 'We don't have room for a women's basketball team anymore,'" Pang recounted.
Westmoreland decided to stick with the all-girls formula despite the prevailing sentiment that all-girls schools were a thing of the past, Pang said.
The school has long since recovered from the lean years of shrunken enrollment, which ended when later research once again showed the merits of all-girls education, Pang said.
And administrators remain certain that all-female education offers girls a special advantage.
"In a girls' school, girls are not the audience — they're active participants. They learn earlier that it's good to be smart," said Nanci Kauffman, the assistant head of school and dean of faculty.
Some traditions did not stand the test of time, however. A beloved Christmas pageant was discontinued in the mid-1980s because it sent a strongly denominational message that alienated some community members, Pang said.
"It was kind of a conflict because it was this really important school tradition, but eventually we did get rid of it," Pang said.
And a lecture from mid-century director Margarita Espinosa about how to daintily eat an orange is no longer in the curriculum, Pang said.
However, core values of the college preparatory school have not changed, Pang said.
"The original 'Five C's' include 'charity,' and today we might say community service, but the idea is the same," she said.
The administration is now drafting a plan for the next hundred years, Kauffman said. About $36.5 million has been raised to enhance future education, Sundblad said. Among other uses, the money will fund student trips to China or India to learn about human rights as well as a new fitness and athletics center, she said.