On January 24, 1935 George Gershwin wrote Todd Duncan (who had just been signed to sing the role of Porgy):
"I am leaving for Florida this weekend where I begin the task of orchestrating the opera. I just finished a trio in the last scene for Porgy, Serena, and Maria which I think will interest you very much."
According to Duncan, Gershwin wove into the counterpoint here themes from earlier sections of the opera. However, the trio section of “Oh Bess, Oh, Where's My Bess” was dropped from the show before its Boston opening.
In this last scene of Porgy and Bess Porgy returns to Catfish Row, having been released from jail. When he sings, “Thank Gawd I's home again!” the chorus welcomes him, singing his motif in a variation made from a succession of major chords in root position. Porgy's theme is then taken up by the orchestra, as he crosses the courtyard and goes over to Maria.
In his longest recitative of he opera, Porgy proceeds to hand out gifts to his friends (he won a lot of money shooting craps while in jail). This recitative begins with a harmonically modern, even atonal, section that rises ever higher in pitch (“I keep des eye shut in dat room”). Then comes music in a more lyrical vein (“Don't anybody let on I's home again”), leading into a presentation of Porgy's motif as his bundles are laid on Maria's table.
The first of the gifts is a harmonica, which Porgy hands to one of the children, while the orchestra mimics a mouth organ. Toward the end of this section is a quote from the harmonica-like main idea of “Oh, I Can't Sit Down.” The next gift is a new bonnet for Lily Holmes. It is at this point that “I Got Plenty O' Nuttin'” becomes the accompaniment to Porgy's recitative. When, unaccountably to him, his friends begin leaving (they know that Bess has left him), he tells the story of his jailhouse crap game to keep them crowding around. Porgy then calls out for Bess and now, against his recitative, the accompaniment is the “Bess, you Is My Woman Now” music. It is when Porgy sees Serena with the baby Bess had been caring for that he realizes Bess is gone.
“Oh, Bess, Oh Where's My Bess,” marked Andantino con molto calore, is sung solo at first by Porgy. He then sings it as a trio with Serena and Maria. As a solo it is just twenty-two bars long. As a trio it is much extended. What is perhaps its most beautiful moment occurs at the point in the trio where Porgy sings “I counted the days”—when there is a sudden shit from E to B-flat minor that creates a great richness of feeling. This idea is developed at length and with much harmonic variety before the main idea returns, followed by an emphatic coda.