The First American Guitar Congress, held last Tuesday through Saturday at the University of Maryland, was a resounding success. Instrumental mastery combined with spontaneous vitality was the constant in five concerts that were thematically designed, but sufficiently varied and open-ended to preserve the element of surprise.

While the classical guitar repertoire has a lot of catching up to do to rival those of the piano and violin, it has made tremendous strides of late in both published transcriptions and works written specifically for the instrument. Thursday and Friday evening's performances in particular proved this point, and showed that the possibilities of guitar literature can extend as far as the imagination of composers and arrangers.

Michael Newman and Laura Oltman moved from the crisscrossing melodic ideas of a real guitar piece, Rodrigo's "Tonadilla," to bring a symphonic breadth using just 12 strings in a zestful arrangement of the Overture to Rossini's "The Barber of Seville."

In contrast, Peter Segal and flutist Janet Ketchum focused on mood, rather than virtuoso fireworks, in Villa-Lobos' "Bachianas Brasileiras" No. 5 and a work composed for them, "Primavera After Botticelli" by Michael White.

*Guitar Congress president Eliot Fisk and bassist Gary Karr won over the Tawes Theatre audience Thursday evening with their arrangement of Schubert's Arpeggione Sonata. Rarely has this turbulent little gem sounded so fresh; Karr's playing was fiery, while Fisk supported beautifully, making the substitution of a guitar for the normal piano accompaniment seem like a blessing.

Fisk figured prominently in Friday's concert (at the National Academy of Sciences), which charted the classical guitar through various ages and a maze of idioms. In four sonatas by Domenico Scarlatti, Fisk convincingly showed how these keyboard works' stylistic elements transfer to the guitar. The last sonata, a terrific display for the nimble of finger, was dispatched with an efficiency that proclaimed "top this!" The challenge was met by David Starobin, who received a standing ovation (led by Fisk) for his phenomenal reading of Elliott Carter's "Changes," avant-gardism at its most oblique and relentless.

Douglas Niedt took a more popular approach in works by Richard Rodgers and Duke Ellington as well as a vigorous "Carioca" arranged by Jorge Morel, one of the participants at Wednesday night's Latin American Heritage program. Morel himself won over the crowd with his own dances and three taken from "West Side Story."

The dance reached its apex in a set by Laurindo Almeida, whose unique brand of "marriage music" wed classical themes with Brazilian samba rhythms.

"Clair de Lune" and themes from Mozart's 40th Symphony were so treated, and just as it seemed that Almeida was going to samba-tize everything, he pulled an ace from his sleeve, combining Beethoven's "Moonlight" Sonata on the guitar with Thelonious Monk's " 'Round Midnight" played by bassist Thomas Cecil.

*Saturday wound up the congress in grand, at times tongue-in-cheek, style. The Los Angeles Guitar Quartet's intriguing performance of Paul Dresher's minimalist Quartet for Guitars led into one of the week's highlights, "El amor brujo," by Manuel de Falla.

Guitarist Ricardo Iznaola had given an explosive rendition (literally, as he broke a string in a heated passage) of the "Fire Dance" portion Wednesday, but the Los Angeles Quartet presented the ballet in full.

A more colorful chamber version, in which all the flamenco and gypsy touches remain intact, would be difficult to conceive, let alone achieve. Another of the week's many standing ovations brought, what else, Earl Scruggs' "Foggy Mountain Breakdown," complete with quotes from "The Yellow Rose of Texas" and the "Bonanza" theme.

Although standing ovations may seem commonplace, the gesture takes on significance when a large percentage of the audience consists of guitarists. It was indeed too bad that the congress players who participated in a guitar orchestra of about 100 strong couldn't reward themselves after they had finished Vivaldi's Concerto Grosso in B Minor. That task was carried out by the grateful audience.