diff --git a/lib/shared/dm-ops/create-entry-spec.js b/lib/shared/dm-ops/create-entry-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/dm-ops/create-entry-spec.js
@@ -0,0 +1,90 @@
+// @flow
+
+import uuid from 'uuid';
+
+import type {
+  DMOperationSpec,
+  ProcessDMOperationUtilities,
+} from './dm-op-spec.js';
+import type { DMCreateEntryOperation } from '../../types/dm-ops.js';
+import type { ThickRawEntryInfo } from '../../types/entry-types.js';
+import { messageTypes } from '../../types/message-types-enum.js';
+import { updateTypes } from '../../types/update-types-enum.js';
+import type { EntryUpdateInfo } from '../../types/update-types.js';
+import { dateFromString } from '../../utils/date-utils.js';
+import { rawMessageInfoFromMessageData } from '../message-utils.js';
+
+function createMessageDataFromDMOperation(dmOperation: DMCreateEntryOperation) {
+  const { threadID, creatorID, time, entryID, entryDate, text } = dmOperation;
+  return {
+    type: messageTypes.CREATE_ENTRY,
+    threadID,
+    creatorID,
+    time,
+    entryID,
+    date: entryDate,
+    text,
+  };
+}
+
+const createEntrySpec: DMOperationSpec<DMCreateEntryOperation> = Object.freeze({
+  notificationsCreationData: async (dmOperation: DMCreateEntryOperation) => {
+    const messageData = createMessageDataFromDMOperation(dmOperation);
+    return { messageDatas: [messageData] };
+  },
+  processDMOperation: async (dmOperation: DMCreateEntryOperation) => {
+    const { threadID, creatorID, time, entryID, entryDate, text, messageID } =
+      dmOperation;
+
+    const messageData = createMessageDataFromDMOperation(dmOperation);
+    const rawMessageInfos = [
+      rawMessageInfoFromMessageData(messageData, messageID),
+    ];
+
+    const date = dateFromString(entryDate);
+    const rawEntryInfo: ThickRawEntryInfo = {
+      id: entryID,
+      threadID,
+      text,
+      year: date.getFullYear(),
+      month: date.getMonth() + 1,
+      day: date.getDate(),
+      creationTime: time,
+      creatorID,
+      thick: true,
+      deleted: false,
+      lastUpdatedTime: time,
+    };
+
+    const entryUpdateInfo: EntryUpdateInfo = {
+      entryInfo: rawEntryInfo,
+      type: updateTypes.UPDATE_ENTRY,
+      id: uuid.v4(),
+      time,
+    };
+
+    return {
+      rawMessageInfos,
+      updateInfos: [entryUpdateInfo],
+    };
+  },
+  canBeProcessed(
+    dmOperation: DMCreateEntryOperation,
+    viewerID: string,
+    utilities: ProcessDMOperationUtilities,
+  ) {
+    if (utilities.threadInfos[dmOperation.threadID]) {
+      return { isProcessingPossible: true };
+    }
+    return {
+      isProcessingPossible: false,
+      reason: {
+        type: 'missing_thread',
+        threadID: dmOperation.threadID,
+      },
+    };
+  },
+  supportsAutoRetry: true,
+});
+
+export { createEntrySpec };
diff --git a/lib/shared/dm-ops/dm-op-specs.js b/lib/shared/dm-ops/dm-op-specs.js
--- a/lib/shared/dm-ops/dm-op-specs.js
+++ b/lib/shared/dm-ops/dm-op-specs.js
@@ -5,6 +5,7 @@
 import { changeThreadReadStatusSpec } from './change-thread-read-status-spec.js';
 import { changeThreadSettingsSpec } from './change-thread-settings-spec.js';
 import { changeThreadSubscriptionSpec } from './change-thread-subscription.js';
+import { createEntrySpec } from './create-entry-spec.js';
 import { createSidebarSpec } from './create-sidebar-spec.js';
 import { createThreadSpec } from './create-thread-spec.js';
 import type { DMOperationSpec } from './dm-op-spec.js';
@@ -34,4 +35,5 @@
   [dmOperationTypes.CHANGE_THREAD_SETTINGS]: changeThreadSettingsSpec,
   [dmOperationTypes.CHANGE_THREAD_SUBSCRIPTION]: changeThreadSubscriptionSpec,
   [dmOperationTypes.CHANGE_THREAD_READ_STATUS]: changeThreadReadStatusSpec,
+  [dmOperationTypes.CREATE_ENTRY]: createEntrySpec,
 });
diff --git a/lib/types/dm-ops.js b/lib/types/dm-ops.js
--- a/lib/types/dm-ops.js
+++ b/lib/types/dm-ops.js
@@ -40,6 +40,7 @@
   CHANGE_THREAD_SETTINGS: 'change_thread_settings',
   CHANGE_THREAD_SUBSCRIPTION: 'change_thread_subscription',
   CHANGE_THREAD_READ_STATUS: 'change_thread_read_status',
+  CREATE_ENTRY: 'create_entry',
 });
 export type DMOperationType = $Values<typeof dmOperationTypes>;
 
@@ -370,6 +371,29 @@
   | DMSendTextMessageOperation
   | DMSendMultimediaMessageOperation;
 
+export type DMCreateEntryOperation = {
+  +type: 'create_entry',
+  +threadID: string,
+  +creatorID: string,
+  +time: number,
+  +entryID: string,
+  +entryDate: string,
+  +text: string,
+  +messageID: string,
+};
+
+export const dmCreateEntryOperationValidator: TInterface<DMCreateEntryOperation> =
+  tShape<DMCreateEntryOperation>({
+    type: tString(dmOperationTypes.CREATE_ENTRY),
+    threadID: t.String,
+    creatorID: t.String,
+    time: t.Number,
+    entryID: t.String,
+    entryDate: t.String,
+    text: t.String,
+    messageID: t.String,
+  });
+
 export type DMOperation =
   | DMCreateThreadOperation
   | DMCreateSidebarOperation
@@ -384,7 +408,8 @@
   | DMRemoveMembersOperation
   | DMChangeThreadSettingsOperation
   | DMChangeThreadSubscriptionOperation
-  | DMChangeThreadReadStatusOperation;
+  | DMChangeThreadReadStatusOperation
+  | DMCreateEntryOperation;
 export const dmOperationValidator: TUnion<DMOperation> = t.union([
   dmCreateThreadOperationValidator,
   dmCreateSidebarOperationValidator,
@@ -400,6 +425,7 @@
   dmChangeThreadSettingsOperationValidator,
   dmChangeThreadSubscriptionOperationValidator,
   dmChangeThreadReadStatusOperationValidator,
+  dmCreateEntryOperationValidator,
 ]);
 
 export type DMOperationResult = {