Husband-and-wife teams in the arts are nothing new but Allen and Pat Ahearn give that pattern a new twist: They deal in antiquarian books and miscellaneous art work at their combination bookstore and gallery called Quill & Brush in Bethesda.

Since opening Quill & Brush in March 1976, Allen has sought out and bought books that Pat then resold. As the bulky book stock grew, the Ahearns had to move in September 1977 from a country store in Olney to their present, more spacious quarters in Bethesda.

While allowing the book stock to grow, Allen has been careful not to deprive Pat of wall space for the six shows she mounts each year. Her purpose, she said, is to provide an "intermediate exhibition opportunity for artists out of school but who could not quite interest the hard-to-get-into galleries in downtown Washington."

The Ahearns are anxious to support -- with money or space -- artists in the "Washington perimeter. If we don't, everything will end up downtown and we are not sure that's best for people out here who want to see art or deal in books," said Pat.

Herself an accomplished artist, Pat returned to art school several years ago to learn "who was doing what in the current art market."

Collectors of either art or books who patronize the Ahearn's Quill & Brush have certain characteristics, said Pat. Only one member of a family tends to collect and most are men. Pat added she has been increasingly amazed by the number of very young but knowledgeable collectors.

One recommendation the Ahearns have to make to husbands and wives who contemplate a joint venture in an arts-related business is that "they ought to be good friends because they are spending much time together," said Pat.

Allen, who quit his job at the Defense Department to devote himself full-time to Quill & Bruch, feels splitting duties that do not overlap reduces the possibility of conflict.

Recently, an important book auction with 74 floor bidders required the Ahearns to work together on promotional advertisements and preauction details. In addition, Allen wrote a book, "The Book of First Books," that defined and catalogued rare publications, and provided bidders with advice on identifying first editions and explanations about publisher practices.

Having blended their operation into a harmonious whole, the Ahearns plan to upgrade their stock, perhaps acquire their own building and eventually train their daughter Dyane, 13, to take over their business.

Opening April 2 at Quill & Brush is a photographic exhibition of James R. Messenger entitled, "Portraits of the Famous and Not-so-Famous." The bookstore-cum-gallery is located at Bethesda Square, 7649 Old Georgetown Rd.