Alexandre Vassiliev has the day, off. Instead of the eighteenth-century silk brocade waistcoat pinned with a Victorian mourning brooch he usually wears, the Paris-based Muscovite is dressed down in a gray thermal top, white jeans and a pair of black blunt-nosed motorcycle boots. If all you knew were the Sitwellian Vassiliev who views the world through a gilded lorgnette strung on a pocket chain, you might have trouble recognizing him.

For today the thirty-five year old fashion historian and designer of sets and costumes for dramas and operas from Salt Lake City to Reykjjavik is taking a backseat to his house and collections. Three smallish rooms in an Art Deco building on the outer limits of Paris's fifteenth arrondissenent are the unlikely vitrine for the more than three hundred vintage dresses (as well as other types of clothing and parts of dresses) Vasiliev began amassing in Moscow before he was even a teenager. Spanning 1740 to 1930, the collection has grown to include French and English designs, though half of it-and the most important part historically is from nineteenth-century Russia. Any museum would be thrilled to have it.

“I live with period clothes - they're part of my everyday life," says Vassiliev in a histrionic drawl that threatens to shatter his apartment”s romantic, richly layered atmosphere of pre-revolutionary White Russia. “I know it's madness, but living in a museum is what I like. I work at home, so if it's a production of, say, Offenbach's Tales of Hoffman I'm designing for, I have at hand just the right dress from which to copy, line for line, the cut of a boned bodice. Of course, if you don't understand cut, you're cooked. That's why ballet companies and opera houses from all over the world come to me, for my knowledge of period costume and insistence on historical accuracy. That, and a certain poetic nostalgia for the Ballets Russes."

Vassiliev's ancillary collection of accessories ensures that his costumes, whether for The Queen of Spades for the Ballet West in Utah or Anna Karenina for the Hong Kong Ballet, are true to their epoch, right down to the last button, parasol, glove, far and rope of pearls. “Authenticity and lavish productions are Alexandre's great specialties" says Andre Prokovsky, the choreographer of Spades, which opens in Salt Lake City on October 28. “Since the work is based on the novel by Aleksandr Pushkin and set in St. Petersburg in the Empire years of the beginning of the last century, obviously Alexandre is especially suited to it."

"He's wildly imaginative, and his knowledge of everything pertaining to costumes is astounding," says Vassiliev's good friend Leslie Caron. "He knows how dresses have been built throughout the centuries, and he knows just by fingering fabric how it will behave when it's cut. His attention to detail also sets him apart - the period accessories are always exactly right."

These days Vassiliev's knowledge is being funneled into a Wiesbaden State Theater House production of Swan Lake set for February. Drawing inspiration from the moody, Gothic-flavored works of Rossetti and Alma-Tadema, he says he is having a good time manipulating pleated textiles that change color.

The collections that serve as reference material for Vassiliev supply as much of the decoration in his apartment as the furniture and objects. From his vast stock of evening slippers, a pair bought in Istanbul and stitched from a cashmere shawl and purple wool imitating broadtail is posed on a Directoire chair in the cochineal-papered salon. The other elements in this casual, sentimental still life are a portrait by the Ecole Francaise painter Amadeo Gras propped up against the Austrian chair's cane back and a well-worn album of photographs of the Russian imperial court. In the bedroom, painted Lanvin blue, a wall case that belonged to his late friend the Russian poet Irina Odoevtzeva frames dozens of eye-filling examples of Empire, Louis-Philippe and Napoleon III glass beadwork. He notes that, because beadwork may be the only applied art that doesn't fade with age, the purses, garters, suspenders, bottle covers and wallets are perfectly intact, save for the odd missing bead. The wall case is stripped of its glass front so that, while researching a production, Vassiliev has easy access to its contents.

Throughout the apartment are antique Anatolian kilims, burnished brass-and-copper samovars, pictures crowded hugger-mugger on the walls, and substantial, exuberantly carved mahogany furniture. "My idea was that the apartment should look like an estate in the Russian countryside somewhere between St. Petersburg and Moscow at the time of Turgenev, meaning the late 1840s-my favorite period in furniture," says Vassiliev. "The house I had in Moscow before moving to Paris was very much the same." Among the pieces typical of those the Russian aristocracy might have had in the last century are a mahogany table with a dolphin base that finishes amusingly in lion's paws and a straight-backed sofa covered in claret velvet, adorned with eagles and ending in swooping rolled arms.

Vassiliev sees his success as a designer as having iron links to his life as a collector. "There is no question I never would have made it if I hadn't had this mass of documentary things to back me up. Cecil Beaton and Andy Warhol were famous collectors; my collections inform my work in the same way their collections informed theirs."

The son of a costume and set designer for the Bolshoi and of an actress who was a friend of Chekhov's widow, Vassiliev took his baby formula in his mother's dressing rooms. A family friend, Alice Vronska, was a ballerina who danced with Anna Pavlova for Czar Nicholas 11. "My parents were both very well known," he says, "and we lived in an old and spacious flat in Moscow. Although the money they earned would have bought little in the outside world, in Russia at the time it was quite enough to live on comfortably. Certainly I never wanted for anything."

By 1970, Vassiliev says, Russians had become so steeped in the thinking that powered the revolution that they had literally discarded all possessions that reminded them of the country's czarist past, which they viewed as decadent and bourgeois. “There was barely an antiques shop in Moscow as little as twenty-five years ago," he says. "In those days everyone thought old objects and clothing would be useless in the Communist world. And so they threw them in the dustbin."

Twelve-year-old Alexandre, on his way home from school, was right behind them, giddily retrieving icons, silver, books-and dresses. Repairs and laundering fell to his mother. To build his collection he even placed notices in newspapers asking readers to dig into their closets and attics. People responded with offers of kokoshniks, or headpieces, embroidered with pearls and precious stones.

After graduating from Moscow Arts Theatre, founded by Stanislavsky, and working for a year as a designer at the city's Dramatic Art Theatre, Vassiliev arrived in France in 1982. Planning to stay two months, he was shut out of Russia, which denied him an entrance visa, for eight years. "I was considered a cultural danger," he says. “At a time when the official line was that those who traveled to the West could not survive, I was terrifically successful. And I dressed up a lot. I don't think they liked that.”

Success was not instant. Vassiliev's early days in Paris were filled with work, money, lodging and language problems. To stay alive he sang Russian songs with a Slovak friend at the Cafe de la Paix and Les Deux Magots. Slowly he found work at the Theatre de Paris and the Avignon festival. Getting his costume collection out of Russia after a number of frustrating years was a watershed. Little by little he has added to it.