In the seventeenth century, plaster casts, which were essential sources of inspiration and instruction, became a recurring motif in images of Dutch painters’ workspaces, a marker of both intellectual and manual labor. Painters used plaster casts to proclaim their erudite knowledge of antiquity and of Renaissance sculpture that emulated ancient models. Plaster casts also provided a means for ambitious painters to communicate their personal and aspirational ties to other masters. The presence of plaster casts in archival records along with painted depictions of the studio provide insights into the impact of these objects on Dutch artists’ practice and the distinguished lineages they claimed.