BROOKLINE -- Closed nearly 10 years ago, former St. Aidan Parish will soon be the site of 59 units of mixed-income housing. Once completed, the project will provide 20 affordable rental units and 16 first-time homebuyer units.

The church building itself -- once the Kennedy’s place of worship and where John F. Kennedy was baptized -- will be made into nine market-rate triplexes. Many in the community felt strongly that the building should be preserved because of its historical significance.

The groundbreaking for the St. Aidan project, held outside the church May 28, attracted religious leaders including Cardinal Seán P. O’Malley, local and state elected officials, the project’s financial partners as well as representatives from its contractor, Consigli Construction Co., Inc.

The project is one of many developed by the Planning Office for Urban Affairs, a self-sustaining social justice ministry of the Archdiocese of Boston. The office, which celebrates its 40th anniversary next year, has developed 2,300 units of affordable and mixed-income housing, providing homes for more than 10,000 people.

At the groundbreaking, Lisa Alberghini, president of the office, said that the decade of planning this project will be well worth its results -- homes for people of modest means.

“Brookline is a privileged community. To remain rich -- rich in diversity, rich in community, rich in what makes life most important and successful -- you have chosen to share that privilege by taking care of your neighbors in need,” she told city residents. “It means a lot, especially in a community like this one where the people who serve those in the community can often no longer afford to live here.”

The project’s benefits will extend to historic preservation of the church building, open space protection, public access and transit-oriented development, she added.

Then, Alberghini quoted Caroline Kennedy who wrote in the 2003 introduction to “Profiles in Courage” by her father John F. Kennedy, “My father understood the complexity of courage, and he understood its simple power as well. He believed that those that act on principle, regardless of cost, can help inspire future generations.”

Caroline wrote about the courage to compromise and the courage to stay the course, Alberghini added.

“This development is a powerful example of both and of working tirelessly to accomplish shared objectives, even when that gets challenging,” she said.

Many politicians, including Sen. Edward Kennedy who is “steadfast in his support for the development,” made the project possible, Alberghini said.

“Brookline is providing over $6 million in town and federal resources to this development. It is an extraordinary investment into this community and its future,” she said.

Alberghini also praised the hard work of Brookline Selectman Robert Allen, Jr. and Congressman Barney Frank, chairman of the House Financial Services Committee.

“Congressman Frank filed landmark legislation last fall to create a national affordable housing trust fund that is highly targeted to help the most needy,” she said.

Speaking at the podium, Frank said that in 10 years the St. Aidan’s project will be completed and will be home to people who contribute to the town.

“Not only do I like to say, ‘I told you so,’ it is one of the few pleasures that improves with age,” he said. “We’ll all come back here, and the cardinal will lead us in prayer, and I will lead us in ‘I told you so.’”

Alberghini said no one has had more passion for the St. Aidan’s project than Selectman Allen.

Allen told those gathered that the development, a “team effort” that required “incredible patience,” serves as a model for other projects.

“It represents a community willing to welcome affordable housing in a state that is willing to help support such housing and a mission-driven developer willing to work in such an environment,” he said.

Alberghini recognized Msgr. Michael Groden, who founded the Planning Office for Urban Affairs and served as its head for nearly 35 years.

Special recognition was also given to Robert Gallery, Massachusetts president of Bank of America, a strong supporter of the Planning Office. The bank provided $60 million in construction financing and equity investments for its last five developments, enabling the completion of 623 housing units since 2001. Currently, the bank and the Planning Office are negotiating another $60.6 million financing for five more projects currently under development.

Cardinal O’Malley addressed the crowd and told them that the work at St. Aidan’s should “enliven our hearts.”

“Affordable housing makes a great difference in people’s lives,” he said. “Whenever we look to the interests of our neighbors in the community and serve them, we are in a sense God’s own coworkers.”

He also praised the children’s choir from St. Mary of the Assumption School in Brookline who sang “Dona Nobis Pacem” four-voice in Latin and in Hebrew at the groundbreaking.

The pastor at St. Mary’s, Father John J. Ahern, and Brookline Rabbi William Hamilton led the closing prayer.

Rabbi Hamilton, who testified on behalf of the St. Aidan’s development at public hearings, called the choir’s performance “touching.”

“It was a very, very extraordinary moment for many of us from the Jewish faith who were able to participate in this dedication,” he said.