The collection consists primarily of 67 letters by Merrill to Thomas Brown Rudmose-Brown, a friend and the author of French Literary Studies (1917), which contains a chapter about Merrill concerning the Symbolist movement. Also included are 15 letters to Gabriel Mourey, an art critic; three letters to Jean Moréas, a fellow supporter of the Symbolist movement; and two letters to Alfred Mortier, a literary critic and author. Also present is an undated autograph manuscript of a poem by Merrill entitled "Le Vrai Temple," a small selection of miscellaneous material, and a letter by Merrill to an unknown recipient.

The following standard abbreviations, or their variations, are used to identify materials in this collection: ALS = autograph letter signed and AMsS = autograph manuscript signed