“When did we get married?” asks Ellen Lupton, turning to her husband, J. Abbott Miller. “Ninety-one?”

There’s a pause during which both make a visible effort to remember that is born more of good manners than any interest in the actual date. The formalities of the Miller-Lupton alliance are less compelling to the couple than its fruits: two children, a comfortable home, and an intellectual partnership whose impact on the world of graphic design cannot be underestimated.

“Yeah, we’re pretty sure,” says Miller in a voice indicating that he is, in fact, not at all sure. “We’ve been married, we think, 12 years, 13 maybe?”

“Whatever,” Lupton says with a girlish impatience for unimportant details. “We’ve been married for awhile. Eventually the romance thing worked out.” Actually, it worked out following a long working relationship and partly because they work together so brilliantly.

Arguably, Lupton and Miller are to graphic design what Charles and Ray Eames were to industrial design—except that what Lupton and Miller accomplish as a team is matched, if not surpassed, by what they accomplish as individuals. Today, Lupton is the curator of contemporary design at the Cooper-Hewitt, National Design Museum in New York, director of the graduate program in graphic design at the Maryland Institute College of Art (MICA) in Baltimore, and working toward a doctorate in communication design. She has created a name for herself by curating exhibits like Cooper-Hewitt’s National Design Triennial and “Skin: Surface, Substance, and Design” that are vast in their breadth and detail, exhaustively researched, and sophisticated in their examination of culture through the prism of its objects. She is also the author of user-friendly websites like her blog, design-your-life, and books like Thinking with Type, a handbook (scaled to the human hand) on how to use graphic design to develop and communicate ideas. Miller, who grew up in Indiana, is the editor and designer of the engrossingly uncategorizable 2wice magazine and a partner at the international design firm Pentagram.

Lupton and Miller met in 1981 in Nick Marsicano’s first Monday-morning drawing class at Manhattan’s Cooper Union. Lupton, who came in as a painter, and Miller, who was studying sculpture, film, and design, discovered a mutual interest in theory and criticism, and wondered why graphic design wasn’t engaging big theoretical issues the way architecture was. “We were really brainy designers, which wasn’t dominant at all at that time,” says Lupton. “We thought design was this incredible discovery as a field, and yet no one was making it interesting. There was so much work to be done.”

Following graduation, the pair set up an after-work think tank called Design Writing Research that, by 1989, had become a day job. The results of this first decade of experimentation were eventually published in a book of the same name, which has become a staple of the field. At first, the collaboration was a laboratory for ideas; partly they wondered whether design could be critical and successful. Within a few years they had their answer, in the form of the Chrysler Award for Innovation in Design.

With son, Jay, 11, and daughter, Ruby, 7, the Lupton-Miller family now lives in Baltimore so that Lupton can work at MICA. Their Bolton Hill neighborhood borders two colleges and is lined with trees and red-brick town houses. Built around 1885, their house has high ceilings and walls lined with books and art. Lupton’s basement office is a warm clutter of papers and orange folders. Her other office is minutes away in MICA’s Brown Center, an exploded box made of sheer gray glass. Miller spends two days a week at Pentagram’s New York office. His satellite Baltimore office is a storefront facing their house, where he works with two young designers.

The pair still share ideas, but full-throttle collaborations have become less frequent. (Recently, they worked together on an exhibition called “Swarm” at the Fabric Workshop and Museum in Philadelphia.) The only issue that the two seem compelled to revisit again and again, both together and separately, is their vision of what and who a graphic designer is.

Lupton’s websites are nakedly accessible, a rich brain dump, while Miller’s work is contained in expensive artifacts that must be sought out (2wice isn’t easy to find); however, Miller is an aesthete without seeming precious and Lupton is a populist who can be intimidating. She is more visionary, and more frustrated by practical limitations. Miller must strike this balance all the time at Pentagram, which is famous for its deft interleaving of the mainstream with the utopian in both its client list and an unusual cooperative business model.

“We complement each other,” says Miller, “and it’s been like that from the beginning.”

More involved in writing and in identifying what’s going on in the design world at a high level, Lupton sees herself as a writer who also knows how to design. “I use design as a tool to get out my messianic message about design,” she says. “Abbott is more of a form maker.”

“I’m more of a formalist, fascinated by a chair or a building,” says Miller. “I don’t expect people to understand why I’m interested in design—I’m more willfully obscure.”

“I want everyone to hear the good news,” Lupton says, turning to him, “and you’re more like the high priest. You’re Murray Moss, and I’m Target.” Miller doesn’t relish the rarefied sound of this, but he is more interested in doing design than encouraging others to do it, as Lupton is.

In the end, however, it is their differences that make them important. To Miller and Lupton, design has never been about how things look. With roots in other, related practices, it is a set of techniques capable of generating ideas, as intellectual as it is visual. The old dichotomies of left brain and right are losing ground to their investigations. It is more important to them that they work in the “culture industry” rather than merely the design industry. In the future, Miller anticipates that, instead of making only formal choices, designers will become producers of content and of the meaning behind content; Lupton believes technology will make designers of us all. “I do have an affinity for Ellen’s message,” Miller says. “Design is being outed. Our little world is less and less small every day.” Lupton and Miller are making it so.