Young Girl in Interior, c. 1918-20 is a variant of one of Glackens' favorite compositions, a full-length figure, frequently seated. This piece is a mature work, a culmination of Glackens' explorations of subject and form. The artist focuses on the essential immediacy of his subject, its incidental details, and its humanity, with a gentleness, piquancy and joyousness. The complexity of the composition in an intimate scale is intriguing. Rather than placing the figure against a simple backdrop, Glackens lets the background vibrate with content.

The objects add a personal dimension to the figure. The scene is the Glackens family house in New York. The furniture appears in other family interiors. Yet, while there is a surrounding sense of the room, the scene is focused on the figure. The environment became ultimately secondary to Glackens' sensitive depiction of this young girl. To unify the subject with the background, the graceful contours of the figure echo in the room and give rhythm to the entire composition. The curve of her left arm relates to the curve of the couch back. The position of her feet repeats the lines of the drapes in the doorway. The hemline of her dress echoes the shape of the tabletop.