Named after the two Dartmouth professors largely responsible for the modern development of theatre at the College, this collection was formally dedicated in 1983. It includes approximately twenty thousand programs, playbills, and cuttings, almost ten thousand published plays, the Barrett Clark Collection of French, German, and British plays of the late nineteenth and early twentieth centuries, and French plays from the MacKaye family from the late nineteenth century. There are also approximately forty linear feet of clippings and information covering actors, set and costume designers, producers, directors, architecture, national theatres, reviews of plays and the like.

A folder-level listing of theatrical clippings and information in the Williams/Watson Collection at the Dartmouth College Library can be found at Theatre Clippings Collections (Thespis): Search. An index to the Williams/Watson Theater Collection can be found here Theatre Program Collection (Playbills): Search.