Little Girl in a Blue Armchair (French: Petite fille dans un fauteuil bleu) is an 1878 oil painting by the American painter, printmaker, pastelist, and connoisseur Mary Cassatt.

The museum page provenance suggests the painting was possibly shown at the Fourth Impressionist Exhibition 1879 as Portrait de petite fille.

So when Edgar Degas invited her to join the Impressionists the same year, a group similarly disaffected by the Salon system, she accepted with eagerness.

[10] The painting is described as "it dazzles with its predominant hue of deep turquoise" and has been regarded to be a masterpiece by Karen Rosenberg in a New York Times review.

Degas presented her with a pup he had procured from fellow Impressionist Ludovic-Napoléon Lepic, a dog lover who bred them, and Cassatt went on to keep them the rest of her life.

[16] Germaine Greer calls it Cassatt's first real stunner: "As an icon of the awfulness of being at once controlled by adults and ignored by them, this bold work could hardly be bettered",[17] a view echoed by Ben Pollitt in his description of the painting as capturing the huffing and puffing tiresomeness that a child feels within the social constraints of an adult world.

The entire painting shows Degas' influence in the asymmetrical composition, the use of pattern, and the cropping of the image in the manner of the Japanese prints he had introduced Cassatt to.

He finds the picture an image of the contented boredom of a comfortable bourgeois life, although the slightly languid and provocative pose of the child is disconcerting.