"So much has changed for the better for dance in the last 20 years, it's really incredible," says choreographer Robert Joffrey, whose own ballet company is drawing nightly crowds in excess of 3,500 to Wolf Trap for its current engagement, ending this evening.

"When I started out with my first company in 1956 on our first tour, we had six dancers - among them Jerry (Gerald) Arpino and Glen Tetley. We went to every whistle stop you can imagine and we performed in old movie houses, high school auditoriums, gymnassiums. I remember one place had this orchestra pit with a huge organ smack in the middle of it - the orchestra players had to be split in half, and the conductor stood on the organist's stool to be seen.

"Nowadays, everywhere you go in this country there are these big new performing arts complexes, with beautiful facilities of dance. And dance needs to be in the right setting. That's one of the things I like so much about coming to Wolf Trap. The stage is enormous, and the floor has a fine bounce to it - we can do anything there, unlike say, the Greek Theater in Los Angeles, where you can't fly any scenery and can't use half your sets."

Starting out with six dancers and ending up as the nation's third largest ballet proupe, with a budget approaching $4 million, is a key to the Joffrey personality. Persistence isn't his middle name, but it just as well might have been. Actually, the Seatle-born dancer's full name as Abdullah Jaffa Anver Bey Kahn, but like so much about Joffrey, it's undergone a professional transfiguration.

By the early '60s, Joffrey had built his company into a formidable ensemble which received invitations to tour the Soviet Union and the Near East. In 1964, he lost the whole outfit - dancers, choreography, sets, costumes and music - in a tiff with his millionaire patrones Rebekah Harkness over artistic sovereignty. Anyone else in his shoes would probably have thrown in the towel for good. But in a year's time, Joffrey and his choreographer side-kick Arpino had assembled a brand bew troupe, with a fiscal transfustion from the Ford Foundation. Quickly the fledgling company gained a reputation as the swingingest ballet troupe, noted for its adventurous repertoire and the youthful ebullience of its dancers.

Joffrey continues to be one of the ballet world's chief missionaries. He's just now back from Varna, Bulgaria, where he represented the United States at a special seminer aimed at reducing the rampant varieties of classical ballet to standardized versions. Delegates from nearly 20 nations were there, including Russia, Poland, Sweden, France, Canada, Egypt and Israel.

Accompanying Joffrey as his demonstrator was a young dancer, Partricia Miller, known locally as the leading ballerina of Mary Day's Washington Ballet, who Joffrey spied recently at a festival in Augusta, Ga. She has just signed a Joffrey contract, and will join his company officially Spet. 5.

"She did beautifully well at Varna," Joffrey says. "I was very proud of her. And everyone worked extremely hard. We began each day at 9 a.m. and didn't stop till 8 in the evening; in two weeks, we had one day off. Yuri Grilgorovich of the Bolshoi Ballet and I were the co-chairmen of the seminar, and we had Potyr Gusev, the great Russian expert on Petipa, demonstrating original versions of the Russian classics, and Kirsten Ralov, the new associates director of the Royal Danish Ballet, showing us their traditional Bournonville repertoire.

"Though we were just making a beginning, the whole thing was a revelation," say Joffrey. "The famous 'Corsaire' pas de deux, for instance, that everyone does as a big virtuoso number - it turns out it wasn't a pas de deux at all, originally, but a pas de trois. The girl was tossed between two men, a prince and a slave; in the West, nowadays, all we see is the slave. And the 'Black Swan' sequence from 'Swan Lake," too; no one does the original Petipa version we saw, which is very beautiful and uses thematic ideas from the 'White Swan' passages of the ballet. We also saw a fascinating Russian version of 'Giselle' in which the Queen of the Wilis dances Albrecht's wouldn't stand for the competition! And my teaching associate, Meredith Baylis, got all of this on videotape."

The bad news for the Joffrey company lately was the cancellation of a spring season as a "precautionary" measure due to mounting deficits. But the good news seems to outweight it. For the first time, Joffrey has all of his operation - studios, school and offices - in one place, at City Center. Last month, the National Endowment for the Arts gave Joffrey a $450,000 "challenge grant," to help bolster its cash reserve.

This fall, the company tackles its most ambitious season to date, including its first full-length ballet, a version of "Romeo and Juliet" by the young Argentinian choreographer, Oscar Araiz. "He uses the complete Prokofiev score, but it's not at all conventional. There's no set, for instance, and there'll be three dancers representing three aspects of Juliet - the child, the romantic and the tragic heroine. It's a big step for us, and a big gamble." But that's the name of the Joffrey game.