diff --git a/chrome/content/zotero/xpcom/data/items.js b/chrome/content/zotero/xpcom/data/items.js
index 0f869f7bbc..ca54cce62b 100644
--- a/chrome/content/zotero/xpcom/data/items.js
+++ b/chrome/content/zotero/xpcom/data/items.js
@@ -189,6 +189,37 @@ Zotero.Items = function () {
 	};
 
 
+	/**
+	 * Clear lastRead from all attachments in a library.
+	 *
+	 * @param {Integer} libraryID
+	 */
+	this.clearAllLastRead = async function (libraryID) {
+		let sql = "SELECT itemID FROM itemAttachments WHERE lastRead IS NOT NULL "
+			+ "AND itemID IN (SELECT itemID FROM items WHERE libraryID = ?)";
+		let ids = await Zotero.DB.columnQueryAsync(sql, [libraryID]);
+		if (!ids.length) {
+			return;
+		}
+
+		let items = await this.getAsync(ids);
+		await Zotero.Utilities.Internal.forEachChunkAsync(
+			items,
+			100,
+			async (chunk) => {
+				await Zotero.DB.executeTransaction(async () => {
+					for (let item of chunk) {
+						item.attachmentLastRead = null;
+						await item.save({ skipDateModifiedUpdate: true, skipEditCheck: true });
+					}
+				});
+			}
+		);
+
+		this._lastReadCutoffs.delete(libraryID);
+	};
+
+
 	//
 	// Bulk data loading functions
 	//
diff --git a/chrome/content/zotero/zoteroPane.js b/chrome/content/zotero/zoteroPane.js
index 5a48549b52..8055c9a3e0 100644
--- a/chrome/content/zotero/zoteroPane.js
+++ b/chrome/content/zotero/zoteroPane.js
@@ -2431,6 +2431,25 @@ var ZoteroPane = new function () {
 		}
 	}
 
+	this.clearAllLastRead = async function () {
+		let collectionTreeRow = this.getCollectionTreeRow();
+		if (!collectionTreeRow.isRecentlyRead()) {
+			return;
+		}
+
+		let result = Services.prompt.confirm(
+			window,
+			Zotero.getString('general.warning'),
+			Zotero.getString('recently-read-clear-all-confirm')
+		);
+		if (!result) {
+			return;
+		}
+
+		await Zotero.Items.clearAllLastRead(collectionTreeRow.ref.libraryID);
+	};
+
+
 	/**
 	 * Check whether every selected item can be restored from trash
 	 *
@@ -3347,6 +3366,10 @@ var ZoteroPane = new function () {
 			id: "deleteCollection",
 			oncommand: () => this.deleteSelectedCollection()
 		},
+		{
+			id: "clearAllLastRead",
+			oncommand: () => this.clearAllLastRead()
+		},
 		{
 			id: "deleteCollectionAndItems",
 			oncommand: () => this.deleteSelectedCollection(true)
@@ -3539,13 +3562,18 @@ var ZoteroPane = new function () {
 		else if (collectionTreeRow.isTrash()) {
 			show = ['emptyTrash'];
 		}
-		else if (collectionTreeRow.isDuplicates() || collectionTreeRow.isUnfiled() || collectionTreeRow.isRecentlyRead()
-				|| collectionTreeRow.isRetracted()) {
+		else if (collectionTreeRow.isDuplicates() || collectionTreeRow.isUnfiled() || collectionTreeRow.isRetracted()) {
 			show = ['deleteCollection'];
 			
 			m.deleteCollection.setAttribute('label', Zotero.getString('general.hide'));
 			useHideOrDelete = "hide";
 		}
+		else if (collectionTreeRow.isRecentlyRead()) {
+			show = ['deleteCollection', 'clearAllLastRead'];
+
+			m.deleteCollection.setAttribute('label', Zotero.getString('general.hide'));
+			useHideOrDelete = "hide";
+		}
 		else if (collectionTreeRow.isHeader()) {
 		}
 		else if (collectionTreeRow.isPublications()) {
diff --git a/chrome/content/zotero/zoteroPane.xhtml b/chrome/content/zotero/zoteroPane.xhtml
index 62de1383fd..2aec7342db 100644
--- a/chrome/content/zotero/zoteroPane.xhtml
+++ b/chrome/content/zotero/zoteroPane.xhtml
@@ -966,6 +966,7 @@
 				</menupopup>
 			</menu>
 			<menuitem class="zotero-menuitem-delete-collection"/>
+			<menuitem class="zotero-menuitem-clear-all-last-read" data-l10n-id="collections-menu-clear-all-last-read"/>
 			<menuitem class="zotero-menuitem-move-to-trash"/>
 			<menuseparator/>
 			<menuitem class="zotero-menuitem-export"/>
diff --git a/chrome/locale/en-US/zotero/zotero.ftl b/chrome/locale/en-US/zotero/zotero.ftl
index df65a30cbf..7cbe88d020 100644
--- a/chrome/locale/en-US/zotero/zotero.ftl
+++ b/chrome/locale/en-US/zotero/zotero.ftl
@@ -185,6 +185,9 @@ collections-menu-show-recently-read =
     .label = Show { recently-read }
 item-menu-remove-from-recently-read =
     .label = Remove from { recently-read }…
+collections-menu-clear-all-last-read =
+    .label = Clear All Last Read…
+recently-read-clear-all-confirm = All Last Read dates in this library will be erased.
 collections-menu-rename-collection =
     .label = Rename Collection
 collections-menu-edit-saved-search =