By the time Cassatt exhibited this painting at the eighth and final impressionist exhibition in 1886, her reputation as a painter of mothers and children had been well established. Critics had long commented on her ability to portray her subjects in a tender, yet unsentimental, way: "Oh, my God! those babies! How those portraits have made my flesh crawl, time and again!—A whole passel of English and French smearers has painted them in such stupid, pretentious poses! . . . For the first time, thanks to Mlle. Cassatt, I have seen effigies of enchanting tots, calm and bourgeois scenes, painted with an utterly charming sort of delicate tenderness." Cassatt's focus on a limited range of subjects allowed her to experiment with both the formal elements and painterly qualities of a composition. Her interest in Japanese prints and the process of printmaking can be seen in much of her work after 1883, including Children Playing on the Beach. In this work, Cassatt tightly cropped the scene, tilted the picture plane forward, and reduced the number of objects in the background to draw attention to the two little girls digging in the sand. Absorbed in their activity, they embody the naturalistic attitude prevalent in both art and literature of the time.
Various shades of blue—from the deep electric blue of the dress and shoes to the soft, diffused blue of the ocean—are used throughout the work. Accents of white convey the presence of sunlight bouncing off the dresses, hats, and pails of the little girls. While particular attention is paid to the building of form through color and line in the foreground, the background is reduced to its essential elements through a series of thinly painted scumbles, leaving areas of the priming layer exposed.
Aspects of the painting suggest that it is a nostalgic tribute to Cassatt's beloved sister, Lydia, who died in 1882. Cassatt was so distraught over Lydia's death that she did not paint for six months. Without revealing the identity of the little girls specifically, Cassatt depicted them in a manner that implies that they are related. Playing close together, the girls are comfortable with each other's presence. By positioning them side by side in nearly identical outfits, Cassatt established both a compositional and psychological relationship between the two figures.
As the primary caretaker of her elderly parents and older sister, Cassatt spent much of her adult life juggling the seemingly incompatible roles of nurse-companion and independent artist. In 1884, Cassatt accompanied her ailing mother to Spain to seek the recuperative effects of the seaside climate. Children Playing on the Beach is generally believed to have been painted after her return. Although completed in the studio—x-radiograph studies reveal that Cassatt reworked almost every area of the canvas—the painting nonetheless conveys a sense of spontaneity and freshness. Such coastal scenes were popular among her impressionist contemporaries, but Cassatt rarely delved into the genre. This work, therefore, holds a place of singular importance within her oeuvre.