The two girls face different directions, but immediately struck us with their similar facial features. Cassatt plays on this by dressing them similarly, and their hair styles are also much the same. The composition places us close to the Two Sisters, cropping most of their bodies out. They wear pink dresses, with a pretty fan making its way into the scene. They have pale complexions, with dark hair which is tidyly kept up. Their facial features are small and feminine, and they do not use a great amount of makeup. Behind them is a green pastel background which is loosely done but fits well with the pink tones used elsewhere. It may have been that the artist actually handled this double portrait seperately, then putting the two girls together at a later date. Because the models were a little older than many of the babies that Cassatt sometimes featured, this would have gifted her a little more time to complete the drawing, and therefore she go into more detail and use shorter strokes of pastel.

Cassatt would often speak about the importance of Edgar Degas within her career, and it was his pastels which influenced her work within Two Sisters. She was astounded when she first saw his work in that medium, and immediately understood its qualities. She took to it in the 1890s and appreciated the balance between drawing and painting - where her drawing skills could be combined with colour, whilst also still able to work at speed and without any great overheads that were always brought along with oils. She also appreciated how it brought in a soft finish that suited her portraits of young women and children, which would become the most frequent genre used within her career.

It was at the 2005 auction event known as American Paintings, Drawings and Sculpture in New York in which Two Sisters came up for sale. It received a guide price of $400,000-$600,000 and ultimately surpassed that, underlining the growing interest in this artist which today has risen to an even higher level. Some of the other highlights from the auction, in which many millions of dollars were ultimately spent, included Mrs Theodore Atkinson, Jr (Francis Deering Wentworth) by John Singleton Copley, Montauk Light by Childe Hassam, Purtud: Fir Trees and Snow Mountains by John Singer Sargent and also Central Park by Maurice B. Prendergast. There were also a number of other Cassatt artworks included here, and she continues to be one of the most important American artists in history, with a growing following in the younger generations who want to see female painters achieve greater exposure.