Opera lovers and fans of musical theater who want to expand their range can make the short hop to Bard College’s Frank Gehry-designed Sosnoff Theater, where Leon Botstein and the American Symphony Orchestra present a bill of masterworks by modernist composer Karol Szymanowski beginning Friday.

The opera “King Roger (The Shepherd)” and the ballet “Harnasie” highlight the Summerscape Festival’s “Prokofiev and His World,” and because the two composers knew one another (and were born in regions now part of the Ukraine), the festival is shedding welcome light on Szymanowski. “He’s the greatest Polish composer since Chopin,” Mr. Botstein said in an interview with The New York Sun, “and is one of the great orchestrators, with an unbelievable sensibility and refinement.”

Szymanowski worked regularly in Paris and in Vienna, where Strauss was an early influence, and traveled to America in the 1920s, when Artur Rubinstein performed his piano music and renowned violinist (and Juilliard teacher) Pavel Kochanski played his compositions in New York, Boston, and Chicago. He wrote four symphonies and two violin concerti. According to Mr. Botstein, Béla Bartók admired Szymanowski “and believed that he had learned from Szymanowski how to use the violin.”

The three-act opera “King Roger” had its premiere in Warsaw in 1926 and tells the tale of the Sicilian king faced with a prophetic shepherd who is enthralling Roger’s people and who comes to entrance the queen, Roxana, and then Roger himself. “‘King Roger’ is Szymanowski’s masterpiece; it’s a psychological drama, as opposed to a dramatic story,” Mr. Botstein said, emphasizing that the shepherd’s ideology is “of Dionysian religion, advocating sensuality, love, and nature. Roger is presented with this prophet in similar ways to Bach’s ‘St. John Passion,’ as the crowd considers him a heretic. Roger has an Arabic advisor, Edrisi, who counsels caution but sympathy, and his wife is fascinated. In the third act, they go off into an ethereal transformation, and the king is left alone, triumphantly embracing the sun, but in fact he’s been abandoned by earthly love. It’s an ambiguous drama, rich and varying in textures with a distinct harmonic language. It deserves a place equal to Bartók’s ‘Bluebeard’s Castle’ in the 20th-century operatic canon.”

Szymanowski’s delicacy and power are evident from the outset. Gorgeous, soft voices of children and adults (sung at Bard by the Summerscape Festival Children’s Chorus and the Wroclaw Opera Chorus) are joined by Roger (baritone Adam Kruszewski). Then the orchestra’s lush edge effects a deft transformation, with tense statements from the brass that resolve toward Roger’s interchanges with his advisers. The splendid role of Roxana (soprano Iwona Hossa) includes an aria so affecting that it remains a staple song in Poland.

Szymanowski worked for years on “Harnasie,” and the ballet was produced at the Paris Opera in 1936, the year before the composer died. In the work, Szymanowski distilled his admiration of culture in the Tatra Mountains of southern Poland, adapting highlander music as well as customs, including the appealing renegades of the title. “It is Bartókian,” Mr. Botstein said, “with a kind of Carl Orff style of orchestral sound with chorus, and an unusual form, with ballet, pantomime, solo tenor, and chorus. Instead of an opera, it’s like a masque or pageant.”

The dance movement in the piece is choreographed by Noémie Lafrance, known for her site-specific works, including “Rapture,” which will be performed at the Fisher Center at Bard in September. In “Harnasie,” martial rhythms introduce the robbers’ swirling dance, and the first act concludes with a wistful fiddle passage that draws the Bride (Emma Stein) home, though she’ll abandon her wedding to join the lead Harnas (Gary Lai).

Mr. Botstein attributes the visual beauty of the production to “the intelligence and imagination of its director,” Lech Majewski, who previously directed Bizet’s “Carmen” at the Polish National Opera. In a phone interview, he spoke of staging “King Roger,” which, though it has connections with the brutal “Bacchae” of Euripides, lacks what Mr. Majewski called “fighting forces.” “It’s more a seductive piece; from the moment the shepherd appears, people are seduced by his singsong, his appearance, his glances here and there.” He concentrated on symbolic and ritualistic aspects to bring out the story. “I find in opera that music always provides you with this track, and the images and visions go on this track and they travel.” For “Harnasie,” projections will show the naked rock formations of the Tatra Mountains, which Mr. Majewski called “one of the most beautiful views you could imagine. “‘Harnasie’ borrows heavily from the culture of the Polish highlanders, who dress up amazingly and ride horses, even into church,” he said with a chuckle. “Their music is amazing, and every major Polish composer is indebted to them, and Szymanowski in particular. There are whole chunks of highlander music that he lifts and encrusts into the ‘Harnasie’ music.”