“There wasn’t anything we didn’t touch to bring a level of elegance,” shares designer Jennifer Mabley of the Upper West Side apartment she customized to a tee alongside partner Austin Handler, senior designer Dana Hanley and general contractor Eric Capolino. The task at hand: finessing two units within a newly redeveloped apartment building into a single sleek and sumptuous home fit for a young family.

Having recently completed their Hamptons residence, the firm was well-versed in the clients’ affinity for light finishes and colors. But, as Handler puts it, you can’t exactly bring a beach-house palette to Manhattan. “When working with lighter finishes, you have to make sure that it’s translating as a sophisticated metropolitan home. You have to make your statement with a lot of detail,” he explains. And so, the designers did just that, deploying distinctive millwork, slabs of statement marble, lacquered ceilings and other applications that elevate the architectural interiors to luxuriously bespoke—and decidedly apropos for Manhattan.

In the newly carved-out family room, floor-to-ceiling white oak wraps the walls, creating a nuanced canvas that encompasses a series of discrete closets at one end of the space and a built-in media center at the other. To define the latter, the designers cleverly recessed the television in reeded oak paneling. Shining above, a high-gloss ivory ceiling makes a wow-worthy statement that, depending on the light, mirrors the movement of the Hudson River on view through the room’s vast expanse of north-facing windows. “In the evening, with the reflections, it changes the whole mood of the room,” Mabley shares.

Harnessing the decorative treatment’s luminous capacities, high-gloss ivory ceilings reappear in the living, dining and primary bedroom, while reeded oak paneling and marble interjections repeat at the elevator entry and as accents. Crucial to the continuity of these material through lines was Capolino’s in-house arsenal of fine craftspeople, who were able to “make numerous samples of custom millwork or paint mixes, working within the palette so that the same tone was expressed throughout,” he notes. “We could really home in on the details since we weren’t working with 17 different vendors,” adds Handler. “Eric was amazing and really streamlined the process.”

When it came to decorating the space, “modern organic” is a phrase that frequently came to mind for the team, inspired in large part by the fine artworks they sourced early in the design process. Take the compelling painting of tree bark by artist Kristin Leachman in the family room, which the designers devised an earthy palette around, pulling its soft grays and browns for the luxe mix of fabrics. Similarly, the dining room’s impressive Stanley Boxer work in textured tones of lilac informed the shimmering purple-grays of the chair upholstery—and the hints of soft lavender that thread through the decorative accents in the adjacent formal living room.

Amid such a sophisticated milieu, it’s easy to forget that this home was crafted for a young family—but this, of course, is by design. Sealed stone and millwork choices are innately wipeable, furnishings are softly rounded to avoid bumps and bruises, and textiles and rugs in family spaces are composed of hardy fibers. And, just as tailored as the home’s more grown-up spaces, the children’s bedrooms are worlds unto themselves, replete with colorful wallpapers, whimsical bunk beds and built-ins seamlessly rendered by Capolino and his team.

Thinking back on the project, the designers delight in the level of customization they were able to achieve in a compressed timeline of only six months. For this, they credit the decisive, collaborative nature of their team, Capolino and the clients themselves—a trio Mabley refers to as a triangle of trust. “The more we were seeing what we could accomplish, the more excited we all became. There was this sense of, ‘Let’s keep going! What else can we do to make this great?’” she says. Adds Handler, “There was no script. That’s what made it such an exciting project and so energizing creatively.”