Mutual Muses was an open-source project hosted by Zooniverse that explored the correspondence between two important figures in the twentieth-century art world. Sylvia Sleigh was an American realist painter known for her portraits and, specifically, for her 1973 painting The Turkish Bath. Lawrence Alloway was an English art critic who is credited as the first person to use the term "pop art." Sleigh and Alloway began writing letters to each other in 1948, and they married in 1954. The Getty Research Institute's Digital Art History program digitized a number of letters that the two sent to one another between 1948 and 1953 and these letters have all been transcribed thanks to Zooniverse volunteers. As the team behind this project notes, these letters are not only a highly personal artifact of a couple's romantic entanglements, but also a unique historical resource that provides art historians with detailed and personal accounts of the lives and careers of these two important figures while also tracing the contours of the larger art movements with which they were associated. While the transcription portion of this project is over, these letters are accompanied by a number of contextualizing resources that may appeal to researchers as well as educators interested in using these letters in the classroom. These resources are available via the education tab.