Earlier this week, the Los Angeles Catholic Education Foundation announced a campaign to raise $100 million for Catholic schools in our area.

Catholic education in the United States is in dire straits. A report from Loyola Marymount University in June found that Catholic schools continue to close even though they graduate 98% of their high school students and send almost all of them onto college. In the early 1960s, the U.S. had over 13,000 Catholic schools with 5.5 million students. Today there are 6,900 schools with two million students. In the Los Angeles area, enrollment has fallen by 20% over the past 10 years, to 80,000 students from 100,000. This trend is due not to lack of demand, but to the inability of parents to pay tuition.

The urban poor are more desperate than ever for Catholic education. Urban public schools have failed these families, graduating approximately 30% of Los Angeles high school students in four years. Catholic schools are their best hope—something I know from personal experience.

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Catholic schools shaped my spiritual, intellectual and social growth. This included grammar school (where I got a very good education despite having 55 students in my classroom), high school and then college. I remember vividly my third-grade teacher reading to us for a half-hour every day. It started me on a lifelong love of reading. I remember the ethic of service the nuns and lay teachers instilled in me. I was taught that the poor were not to be pitied—they wanted only to be given the opportunity to succeed. And the fortunate had an obligation to help.

So why are Catholic schools the answer to our urban education woes? Aren't charter schools beginning to help this underserved population? Charter schools are an amazing development, and I've chaired the Alliance for College-Ready Public Schools and the Inner City Education Foundation, both charter advocacy organizations. But not everyone will be able to attend charter schools because the capacity isn't there.

Charter schools are public schools that receive the same dollars as other public schools (in California, $7,500 per student). By contrast, Catholic schools rely on private contributions (averaging $4,000 per student) and tuition (averaging $2,500 per student) from some of our poorest families. In terms of graduation rates, only the very best charter schools in Los Angeles are on par with Catholic schools.

Catholic schools infuse beliefs, values and standards that children will carry all their lives. They provide a safe learning environment for those from high-crime neighborhoods as well as structure and a faith-based education. The schools create a sense of community and an expectation that every child will achieve his or her goals.

Many students in Catholic schools are not Catholic. As Catholic school teachers often say, "We provide this education not because the students are Catholic but because we are." Our faith calls us to it.

So how can we provide the gift of Catholic education to the thousands of struggling families who want it but could never scrape together an extra $2,000 or $3,000 a year? Of the 17,500 applications the Los Angeles Catholic Education Foundation received for financial aid last year, 17,000 qualified for a tuition award. But the foundation could afford to give awards to only 8,400 students. The average income level for a family of four who received tuition assistance last year was $21,500. We believe that if we increase our endowment by $100 million, we will be able to offer scholarships to all deserving children for decades to come.

In the years that I was mayor of Los Angeles, I was interested to find that some of the best people who worked for me had Catholic school experience. My fire and police chiefs were both Catholic school graduates. And I see significant numbers of Catholic school alums in a leadership course I teach at UCLA's business school.

Each of us, no matter what career we have followed, has an obligation to educate the next generation. The education needed for success in our world necessarily includes the basics of reading, writing and math. It must also include the ability to reason, to make good judgments, and to be responsible for our planet and all its peoples. These have been the fundamentals of our Catholic schools for over a century. We must guarantee they are here for generations to come.

Mr. Riordan, who was mayor of Los Angeles from 1993 to 2001, is the founding president of the Los Angeles Catholic Education Foundation.