Nearly every figure on the balcony can be identified. Gustave Caillebotte, seated at lower right in a straw hat, was himself a painter and an enthusiastic rower who had become a close friend of the Impressionists after Renoir met him at Argenteuil, and who later bequeathed his own collection to form the core of what became the Musee d'Orsay^[3]. The man leaning against the balustrade is Alphonse Fournaise, the restaurant proprietor's son, looking toward his sister Alphonsine, who rests her chin on her hand at the railing; Alphonsine had posed for Renoir several times across the years 1875 to 1881 and the Fournaise family had become genuine friends of his^[3]. The remaining figures include the art historian Charles Ephrussi, the actresses Ellen Andree and Jeanne Samary, the Italian journalist Antonio Maggiolo, the amateur artist Paul Lhote, the civil servant Eugene-Pierre Lestringuez, and the model Angele Legault^[2]. It is, in effect, a group portrait of Renoir's actual social world rather than a scene of anonymous Parisians at leisure.

Renoir met Aline Charigot in late 1879, near a dairy shop on the Rue Saint-Georges where she sometimes bought a cheap lunch; she was nineteen, worked as a dressmaker, and lived nearby with her mother^[2][3]. She became his primary model and, later, his wife and the mother of his three children^[2]. Luncheon of the Boating Party is among the first finished paintings in which her portrait clearly appears, seated in the foreground in a fashionable, fanciful hat and holding a small dog; Renoir's son Jean later observed, with some justice, that his father had in some sense been painting his mother's likeness in other models years before the two actually met^[3]. The first work in which Aline's distinctive form appears at all was Oarsmen at Chatou, a study of friends on the same stretch of the Seine that supplied the setting for this later, more ambitious canvas^[2].

The picture combines figures, still life and landscape into a single composition, its richness of form and flickering light praised even by contemporary critics who found other aspects of Impressionism difficult; three reviewers named it the finest painting at the Seventh Impressionist Exhibition of 1882^[1]. The diagonal of the balcony railing splits the canvas into two halves, one densely packed with overlapping figures and conversation, the other left comparatively empty apart from Alphonsine and her brother, a contrast that makes the quieter half read as a deliberate pause within the composition^[1]. Light enters through a large opening in the balcony beside the standing man in the hat, and the white sleeveless tops of the men in the foreground, together with the tablecloth, catch and reflect that light, building a sense of luminosity that runs through the whole scene^[1]. Not every contemporary response was favourable: the critic Albert Wolff wrote in Le Figaro that if Renoir had learned to draw, he would have a very pretty picture, a backhanded jab at exactly the loose, colour-built drawing other critics praised^[1].