Even the name Riverdale evokes the natural beauty of the Bronx neighborhood separated from Manhattan by the Harlem River, and from the New Jersey Palisades by the Hudson. Its steep grades and lush greenery make it seem a world apart from Manhattan, and in fact, many people assume it is not part of New York City.That’s about to change.

Riverdale is on the cusp of a transformation, driven by young professionals looking for value and amenities that other tipping point neighborhoods such as Fort Greene or Harlem lack: quality public schools for students from kindergarten to 12th grade (an important moment for Riverdale was when it got its own public high school in 1999); parks; and convenient transportation to Manhattan by bus, subway, and commuter rail.

“For people who are thinking about having a family, it’s very desirable,” a 34-year-old Web designer, Hal Siegel, said.Mr.Siegel and his wife, Stephanie, a graphic designer who is 29, are preparing to start a family, and recently bought a three-bedroom condominium in Riverdale for $600,000. The unit is in Arlington Heights, a five-story building that is expected to be ready for occupancy in early summer. Mr. Siegel plans to commute to his office on 26th Street using the no. 1 line, a trip that will take 40 minutes each way. Mrs. Siegel works from home.

The Siegels are leaving behind the trendy Smith Street shops and restaurants they live near now, in Carroll Gardens, but they’re charmed by what they have found in their new neighborhood. “There’s a sense of neighborhoodiness,” Mr. Siegel said. “I like the fact that there are places that have been there for years and years.”

The condo the Siegels bought is one of many in development in Riverdale. And while there are many up-and-coming neighborhoods in various parts of the city, few can compete with Riverdale on price.

“Riverdale values are tremendous,” a real estate broker with Atlantic Realty Partners, Peter Bobotas, said. “In Riverdale condos are a new phenomenon, people are just getting the word, while in Brooklyn and Queens that kind of market is there and developing for some time.” Mr. Bobotas’s firm handled sales at Arlington Heights, where two of the nine units are available.

Before young professionals started moving to the area in greater numbers, the influx of Orthodox Jewish families had already begun, and that has made the existing housing market tighter, driving up property values.

Fortunately for prospective buyers, developers have entered the market with a vengeance, with at least one building, Arlington Suites, marketed to Orthodox Jews, and others taking more of a cue from the luxury condos going up in Manhattan.

Almost everywhere you turn, a construction site is bringing noise and dust to the tree-lined streets, which are peppered with a motley blend of single-family houses and red brick apartment buildings.

The most popular spot for the new condominium developments is near the shopping center on Riverdale Avenue. The center features a Chase bank branch, a locksmith, a grocery store that delivers, an independent bookstore, and a handful of places to eat that offer pastries, sushi, kosher steak, and Italian subs.

Another condo development, the seven-story Cambridge Mews, is expected to be ready for occupancy in early summer. It contains 31 units with one-bedroom apartments starting at $329,000 and three-bedroom units starting at $800,000. Designers of the Mews tried to give the building an old, English-style look, adding a stone parapet that echoes the stonework at the 1926 walk-up co-op that is situated up the block, Fieldston Garden, where units rarely come on the market.

Across the street is Westwood Terrace, which aims to provide the luxury and amenities seen in new developments in Manhattan and Brooklyn. It in fact is designed by the same team that worked on the Chelsea Club and the Gretsch Building: designer Andres Es cobar and architect Karl Fischer.

The building with the sleekest look is the 20-story, 65-unit Solaria, which offers floor-to-ceiling glass apartments, most with balconies. When it is completed this fall, the Solaria will be the tallest building in Riverdale. It will also be one of its most expensive, with fivebedroom condominiums costing as much as $3.75 million. Contracts have been sent out for 20% of the units, with the developer marketing the units to a select list of potential tenants. (The sales office isn’t open to the general public.) “The building is a great place for growing families, empty-nesters, and individuals looking for Manhattan quality in Riverdale,” the president of Marketing Directors Incorporated, Adrienne Albert, said.

The feel of the neighborhood has already changed, with the sidewalks filled with many more children than there were four years ago. The 1970s style Chinese restaurants may not be around for long.

But because the new arrivals are drawn to the new construction,perhaps the lives of current residents will not be too disrupted. These are the teachers, nonprofit and arts administrators, and waiters at the Four Seasons who live in the massive white and red brick buildings.A one-bedroom in these buildings, now co-ops, sells for about $180,000 these days – an increase of 150% over the past five years.

And there will be significant price hikes in the luxury developments that have filled in right along the water’s edge, where in small numbers, affluent professionals and empty nesters have been finding refuge from and proximity to Manhattan for years.

Riverdale also has super-wealthy areas with stately castle-like homes. In Fieldston, which recently received landmark status, houses sell for prices between $7 million and $10 million. Parents like the proximity to the elite private schools in the neighborhood: Fieldston, Riverdale Country School, and Horace Mann.

Newer residents are likely to feel most at home near Manhattan College and the College of Mount Saint Vincent, an area with bars – such as the Irish pub An Beal Bocht – that appeal to a younger crowd. But there are a few things lacking in Riverdale. There’s no BAM, for instance, and there is no chic restaurant scene. As a resident of one of the historic mansions in the neighborhood, Susan Morgenthau, said, “When we have guests, we go into Manhattan to eat.”

One place Mrs. Morgenthau hasn’t tried yet is the River City Grill on Riverdale Avenue. It’s the restaurant that developers feature on their Web sites to market the neighborhood and their new buildings. The restaurant itself is pictured with signage and decor that, more than any other Riverdale spot, could meet the standards of the hipsters of Manhattan and Brooklyn.

“Riverdale used to be the best-kept secret,” the restaurant’s owner, Bob Albert, who also owns a stake in the Zagat-rated Jake’s Steakhouse in nearby Kingsbridge and has lived in the area since 1978, said.”It’s definitely not a secret anymore. I’ve never experienced anything like this.”