The Villages, in central Florida, is the world’s largest gated, age-restricted retirement community. Homes are relatively inexpensive, there are organized activities every night of the year, and, with 41 golf courses, you can practice the old swing. In 2000, fewer than 9,000 seniors lived there. Today, more than 100,000 call the Villages home.

But a more meaningful role in urban planning will be determined by an estimated 78 million-strong baby boomer demographic. Currently, more than 10,000 Americans are turning 65 every day, and the senior citizen population, now around 40 million, will more than double over the next four decades. With an even larger Millennial generation propelling a trend that has seen scores of high-density, mixed-use, and infill projects over the last decade, boomers—many of whom once flocked to suburbia to raise children—will add a new dimension to urban revival.

“Some cities are going to have to look at the numbers and say, ‘Okay, in 10 years, 20 percent of our population will be over 65 years old and we need to find ways to adjust accordingly,’ ” says Henry Cisneros, Hon. AIA, former mayor of San Antonio, Texas, and former U.S. Secretary of Housing and Urban Development, who currently chairs the institutional investment firm CityView. “Although New Urbanism didn’t begin with the elderly in mind, the principles of density, walkability, mixed-use, and transit-oriented design all make infinite sense for an aging population.”

A co-founder of the Congress for the New Urbanism and dean of the University of Miami School of Architecture, Elizabeth Plater-Zyberk, FAIA, agrees. “Communities need to think about becoming more intergenerational so that seniors can be as comfortable in society at large as can teenagers who can’t drive,” she says. “The young and old have very similar needs: walkability and accessibility.”

Her firm, Duany Plater-Zyberk & Company (DPZ), planned two communities that helped launch the New Urbanism movement. The Kentlands in Gaithersburg, Md., near Washington, D.C., is a community of around 5,000 residents built on an old farm estate where many original landmarks have been restored as venues for public events. Its commercial districts feature grocery stores, restaurants, offices, shops, banks, and a movie theater.

“We should think not in terms of building retirement communities, but in terms of building communities where the elderly can play an active role, where they are regarded as full-fledged citizens who can actually teach us something,” Robert Davis says. Davis, along with his wife, Daryl, founded Seaside, another community planned by DPZ. The small town has become a quiet breeding ground for progressive development ideas and a touchpoint for planners.

Davis also points to Boston’s Beacon Hill Village, founded in 1999 on principles of an active and self-sufficient lifestyle. Nearly 400 residents pay annual dues for services such as homecare and drivers, which has inspired the creation of nearly 100 similar villages across the country.

Communities everywhere will need to be thoughtful in accommodating a rapidly growing senior population; tax structures and fixed incomes are as critical to keep in mind as zoning laws and accessibility. But the Milken Institute’s 2012 index “Best Cities for Successful Aging” (ranking 359 metro areas based on 78 indicators) shows that some major cities are making progressive steps. Even builders are trying to adjust. Lennar, the Miami-based home building giant, started incorporating multigenerational floor plans into a significant percentage of its new housing stock.

After all, “most of the aging population, especially boomers, will not want to isolate themselves,” Robert Davis says.