THEY MET in 1954 while students at Pratt Institute, the famous Brooklyn art school. Anita Kempler was auditioning for a part in a school production of Chekhov's A Marriage Proposal. The director's name was Arnold Lobel. She got the part, and a year later they married. In the 27 years since, they have occupied side- by-side drawing boards, creating award- winning children's picture books.

The Lobels live in a Victorian townhouse in Brooklyn with their cat, Orson, and work in a bright, airy studio on the top floor. Their two children, both in their twenties, also talented, have moved on. Adam, a video consultant, is a photographer and rock guitarist, and Adrianne is a set designer in New York.

Arnold Lobel, creator of the Frog and Toad books, the 1981 Caldecott Medal-winning Fables and the recently published Ming Lo Moves the Mountain, has emerged as an eminent writer-illustrator. Now Anita's talents as a superb illustrator are finally getting recognition. After years of living and working together, the Lobels in 1978 collaborated for the first time on How the Rooster Saved the Day. Their third and most recent book together, On Market Street, illustrated by Anita, was published last year to critical success. A Caldecott Honor Book, it was also nominated for an American Book Award.

One day recently, in their comfortable living room, decorated with their own and others' paintings and drawings, and Anita's stained glass, the Lobels talked about their work and their lives.

For Arnold, who speaks with a deep, resonant voice and who often sparks his comments with mild irony, teaming up with Anita was somewhat traumatic. "For years I've written and illustrated my own stories. I try not to think visually when I'm writing because if I do I'm going to cheat myself. I always write first. You see, I'm a trained artist, so if I'm writing and I'm also thinking of the pictures then my mind gets confused. I can say to myself, 'You don't have to write this very well because you can draw a picture here.' And that's dangerous because the text of a picture book is very delicate. It has to be delicate and clear and strong, and if I muddle my mind by trying to think of pictures at the same time I'm putting these words down, that would be very bad." COLLABORATION

HOWEVER, ONE DAY a few years back he did think visually while he was writing. He was, he says, writing a kind of European folk tale about a rooster and a farmer. "I thought, 'This is a story Anita could illustrate more successfully than I.' "

"And when I started illustrating his story," says Anita with mock frustration, "he said, 'What are you doing to my story?' "

"Well, for the first time I felt the frustration of not doing it all myself," says Arnold. Years ago, when Arnold was illustrating books written by others, he would never see his partner so there was no temptation to criticize. But with Anita, he was teaming up with a person who was only a murmur away.

The trauma passed, probably because the Lobels have always respected one another's opinion about their work. Says Anita, "He asks me, 'Do you think this arm is too long?' or I'll ask him, 'Should I use a different color on this dress?' We constantly go back and forth. It's nice because if we were alone we could only get the opinions of the art director or the editor, and we only see them every two months or so."

On Market Street, their latest collaboration, grew out of a poster Anita drew for the Children's Book Council for Book Week 1977. It showed a man made of books, an idea she came up with while browsing through book stalls along the Seine during one of their frequent visits to Paris. A London publisher liked it and asked her to create a book from the idea.

"It was a concept book rather than a story book," says Arnold. "It was inspired by a visual image rather than text."

"At first, we thought we'd do a book based on trades--I sew, I bake, this is the shoemaker, this is the candlestickmaker--all very boring," recalls Anita. "Then I thought of the alphabet book--26 letters which allowed me to draw 26 characters."

The result is a shopping spree of letters, each beautifully illustrated in Anita's classical European style with dashing figures in vibrant colors. Arnold's contribution was 16 lines of delightfully complementary verse, which he wrote and refined on a round-trip flight to Los Angeles. SHOW PEOPLE

THE DRAMATIC ARTS brought the Lobels together and it still has a major influence on their work. "Picture books are like screenplays," says Anita. "How do you translate very terse text into some kind of visual context? Really and truly, if you don't know anything about the theater, it is very difficult to illustrate children's books."

Adds Arnold, "All the good illustrators we know, if they are not involved in the theater actively, are certainly enthusiastic theater-goers."

With their reputation as picture-book authors established, the Lobels in recent years have been satisfying their other artistic urges. Anita began taking acting and singing lessons, and did a lot of cabaret shows in New York. She has a theatrical presence with a rich accented voice and exotic East European looks, and has landed several parts in off-Broadway productions. Arnold, meanwhile, is studying singing with a coach for his own pleasure. "I sing music from the 1930s, written by Harry Warren, Noel Coward, Cole Porter. I haven't sung in public yet, but I have this vast repertoire--push the button and I can do it."

When the Lobels appear on panels or at other public functions they invariably are asked the effect on their work of being parents. "I've been asked it so often and I've never been able to give a satisfactory answer," says Arnold. "Certainly being around children and knowing a child's sense of humor is no detriment."

Arnold also notes, however, that some of the most talented people in the business never had children--Maurice Sendak is a bachelor, Edward Lear did not have children, neither did Beatrix Potter nor Lewis Carroll. Besides, says Arnold, "Kids are lousy critics because they're always going to say something you do is wonderful. They know where their bread is buttered."

And, says Anita, "They like the worst things. They have no taste."

Should an author attempt to elevate children's taste or pander to it? "I'm not clever enough to do things in bad taste and neither is Arnold," says Anita, who adds, "You have to be brilliant to present bad taste in a brilliant manner--like pop art or Mad magazine." CHILDHOODS

ANOTHER question often put to the Lobels is whether something in their early years directed them toward their careers.

"When I was a little boy in Schenectady," says Arnold, "I would entertain my friends by telling them stories and drawing pictures for them. I was not good at athletics, but I could do that and it saved me. Then I decided, as all young artists do, that I wanted to be Picasso, so I began painting very serious things. At Pratt I took something called illustration, which I enjoyed, but when I graduated in 1955 and went to employment agencies saying I wanted to illustrate and write children's books, they said, 'There's no money in that.' They were right, because back then there was only Dr. Seuss and a couple of others."

Anita's childhood was so bleak that many of her friends have wondered why it doesn't come through in her art. "I lived in a very bourgeois household in Krak,ow, Poland," she says. "I had a wonderful nanny, and when the war came in 1940 and I was 5 years old, my parents disappeared this way and that, and the nanny took me and my young brother into the Polish countryside --which was primitive, nasty, raw and Catholic. That was on one side and the Nazis on the other. Aside from the fact that there was an outside force that hated us and chased us, I always felt my brother and I were protected by this person who chose to protect us. I loved her and she loved us, and I think that this was very important. I really feel Nanny's affection colors my work, because I don't feel I have to portray the awful bleakness of the time."

Anita and her brother were captured on Christmas Day, 1944, and spent the last months of the war in concentration camps. In 1947, after being shipped from Ravensbruck to Sweden with other prisoners, the children, with the help of a Jewish organization in Stockholm, were reunited with their parents, who miraculously also survived the Holocaust. The family moved to New York in 1952. Anita notes sadly that her nanny died in Poland in 1948. PUSHING CHILDREN'S BOOKS

TO HEAR Arnold tell it, the Russians played a major role in his success story. "When Sputnik was launched in 1957," says Arnold, "America suddenly got a terrible sense of inferiority. Our educational system had failed and we weren't producing scientists. So suddenly all this money and all this interest was pushed into children's books. It was exactly the time when I came into the field, a very lucky coincidence."

At about this time, Arnold met Susan Hirschman, then an editor at Harper & Row, and was given a manuscript to illustrate. She is still one of his editors. Hirschman also encouraged Anita, working as a textile designer, to try children's books.

Then, recalls Arnold, "In the 1960s, thanks to President Johnson's aid to education, libraries found themselves with more money to spend on new books. As a result, publishers were able to give opportunities to a lot of new, young artists and authors working in children's books. A lot of young artists got an opportunity to show their stuff."

"Yes, Arnold," Anita says, "but we know now that a lot of mediocre stuff was also published in the '60s--and some of it we illustrated."

Today, says Arnold, very few artists can support themselves exclusively producing children's books. "That's why a great many of the books are being done by us old guys," he says. "There are fewer young people in the field."

Another change from the old days is the tendency for the same person to write and illustrate a book. "Publishers would get a manuscript from an author and try to find an artist to illustrate it," says Anita. "Now," says Arnold, "it seems that the best illustrators also write their own stories. Maurice Sendak, Jim Marshall, Chris Van Allsburg, who won the Caldecott this year . . ."

"And let's not forget Arnold Lobel," chimes in Anita.

". . . William Steig, who is a brilliant writer and does wonderful pictures, Uri Shulevitz, James Stevenson. . . .' FROG AND FRIEND

CERTAINLY Arnold's most popular creations have been that odd couple, Frog and Toad. In Anita's view, the Frog and Toad books were the first that Arnold "felt very deeply. He was not just manufacturing stories," she says, "he was talking about important subjects like friendship, fear, loneliness, hysteria, doubts, psychosis."

Alas, Arnold has retired the two little friends. "There are four Frog and Toad books," he says, "and there will be forever four. I feel I've extended the friendship about as far as it will go. I don't want to be known only for that, and I don't want to make a product out of them. In fact, there were Frog and Toad products, but they weren't successful. It's very hard to manufacture good stuffed animals and have them sell for under $25. And a particular problem with Frog and Toad was, how could you bring just one home to a child?"

The book for which Arnold won last year's Caldecott, Fables, consists of 20 tales about our finned, feathered and four-legged friends, each ending with a moral. "People resent morals today, with everything sewed up so neatly. But I read lots of 19th-century translations of Aesop and I decided that Fablesneeded morals. I tried not to make them too didactic, and many of them are almost facetious and funny.orce t"

Anita recalls, "He wrote them after breaking his foot in 1978. Every night I would go to dancing class, and when I came home he'd say he had written another story. They took one month to write, and by the time the cast was off, Fables was finished."

Arnold says, "The moral of that is . . . go out and break your foot. It's great for productivity."

The success of On Market Street has produced pressure for another collaboration, but none is in the works. Anita has just finished illustrating an anthology of children's songs called Singing Bee, which will be published in the fall. Arnold has completed a book of original limericks, which is illustrated with fantastic pigs dressed in Victorian garb and is titled Pigericks.

Arnold and Anita's work habits remain highly regimented, if not as rigorous as they once were. Years ago, recalls Arnold, they would work from 9 a.m. until late afternoon, then spend the evening with the children, returning to their drawing boards until 2 a.m. These days they knock off by mid-afternoon.

"My ideal day now," says Anita, "is to work from 9 until 2 in the afternoon at my drawing desk, then go to a rehearsal--if I'm lucky enough to have a part."

"As my number of years have increased my working hours have decreased," says Arnold. "That seems just and pleasant."