A fine rich early proof impression, with the aquatint of the background effectively contrasting with the drawing in soft ground etching. Cassatt's experimentation using soft ground etching and aquatint in the same print presages her later use of these techniques in the color aquatints.

Impressions of Bill Lying on His Mother's Lap are exceedingly rare; we know of only one other impression, of the last state, to appear on the market in recent decades, and know of no other second or early-state impressions.

Mary Cassatt regarded printmaking as a developmental activity, a way to grow as an artist; this perspective was fostered by her colleague and fellow printmaker Edgar Degas. Prints such as Bill Lying on His Mother's Lap were not editioned but created in only a few impressions, and printed personally by Cassatt.