diff --git a/web/modals/threads/create/compose-subchannel-modal.react.js b/web/modals/threads/create/compose-subchannel-modal.react.js
index e0dae6554..0bc2cf5f5 100644
--- a/web/modals/threads/create/compose-subchannel-modal.react.js
+++ b/web/modals/threads/create/compose-subchannel-modal.react.js
@@ -1,190 +1,284 @@
 // @flow
 import * as React from 'react';
+import { useDispatch, useSelector } from 'react-redux';
 
+import { newThread, newThreadActionTypes } from 'lib/actions/thread-actions';
+import { createLoadingStatusSelector } from 'lib/selectors/loading-selectors';
 import type { ThreadInfo } from 'lib/types/thread-types';
+import { threadTypes } from 'lib/types/thread-types';
+import {
+  useDispatchActionPromise,
+  useServerCall,
+} from 'lib/utils/action-utils';
 import { trimText } from 'lib/utils/text-utils';
 
 import Stepper from '../../../components/stepper.react';
+import { updateNavInfoActionType } from '../../../redux/action-types';
+import { nonThreadCalendarQuery } from '../../../selectors/nav-selectors';
 import Modal from '../../modal.react';
 import css from './compose-subchannel-modal.css';
 import SubchannelMembers from './steps/subchannel-members.react';
 import SubchannelSettings from './steps/subchannel-settings.react';
 import type { VisibilityType } from './steps/subchannel-settings.react';
 
 type Props = {
   +onClose: () => void,
   +parentThreadInfo: ThreadInfo,
 };
 
+const getThreadType = (visibility: VisibilityType, announcement: boolean) => {
+  if (visibility === 'open') {
+    return announcement
+      ? threadTypes.COMMUNITY_OPEN_ANNOUNCEMENT_SUBTHREAD
+      : threadTypes.COMMUNITY_OPEN_SUBTHREAD;
+  } else {
+    return announcement
+      ? threadTypes.COMMUNITY_SECRET_ANNOUNCEMENT_SUBTHREAD
+      : threadTypes.COMMUNITY_SECRET_SUBTHREAD;
+  }
+};
+
 type Steps = 'settings' | 'members';
 
 type HeaderProps = {
   +parentThreadName: string,
 };
 
 function ComposeSubchannelHeader(props: HeaderProps): React.Node {
   const { parentThreadName } = props;
   return (
     <div className={css.modalHeader}>
       <div>
         {'within '}
         <div className={css.modalHeaderParentName}>{parentThreadName}</div>
       </div>
     </div>
   );
 }
 
+const createSubchannelLoadingStatusSelector = createLoadingStatusSelector(
+  newThreadActionTypes,
+);
+
 function ComposeSubchannelModal(props: Props): React.Node {
   const { parentThreadInfo, onClose } = props;
   const { uiName: parentThreadName } = parentThreadInfo;
 
   const [activeStep, setActiveStep] = React.useState<Steps>('settings');
 
   const [channelName, setChannelName] = React.useState<string>('');
   const [visibilityType, setVisibilityType] = React.useState<VisibilityType>(
     'open',
   );
   const [announcement, setAnnouncement] = React.useState<boolean>(false);
   const [selectedUsers, setSelectedUsers] = React.useState<
     $ReadOnlySet<string>,
   >(new Set());
   const [searchUserText, setSearchUserText] = React.useState<string>('');
 
+  const loadingState = useSelector(createSubchannelLoadingStatusSelector);
+
+  const [errorMessage, setErrorMessage] = React.useState<string>('');
+
+  const calendarQuery = useSelector(nonThreadCalendarQuery);
+  const callNewThread = useServerCall(newThread);
+
+  const dispatchActionPromise = useDispatchActionPromise();
+  const dispatch = useDispatch();
+
+  const createSubchannel = React.useCallback(async () => {
+    try {
+      const threadType = getThreadType(visibilityType, announcement);
+
+      const query = calendarQuery();
+      const result = await callNewThread({
+        name: channelName,
+        type: threadType,
+        parentThreadID: parentThreadInfo.id,
+        initialMemberIDs: Array.from(selectedUsers),
+        calendarQuery: query,
+        color: parentThreadInfo.color,
+      });
+
+      return result;
+    } catch (e) {
+      await setErrorMessage(
+        e.message === 'invalid_parameters' && announcement
+          ? 'announcement channels currently not available'
+          : 'unknown error',
+      );
+
+      return null;
+    }
+  }, [
+    parentThreadInfo,
+    selectedUsers,
+    visibilityType,
+    announcement,
+    callNewThread,
+    calendarQuery,
+    channelName,
+  ]);
+
+  const dispatchCreateSubchannel = React.useCallback(async () => {
+    await setErrorMessage('');
+
+    const response = createSubchannel();
+    await dispatchActionPromise(newThreadActionTypes, response);
+    const result = await response;
+
+    if (result) {
+      const { newThreadID } = result;
+      await dispatch({
+        type: updateNavInfoActionType,
+        payload: {
+          activeChatThreadID: newThreadID,
+        },
+      });
+
+      props.onClose();
+    }
+  }, [dispatchActionPromise, createSubchannel, props, dispatch]);
+
   const onChangeChannelName = React.useCallback(
     (event: SyntheticEvent<HTMLInputElement>) => {
       const target = event.currentTarget;
       setChannelName(target.value);
     },
     [],
   );
 
   const onOpenVisibilityTypeSelected = React.useCallback(
     () => setVisibilityType('open'),
     [],
   );
 
   const onSecretVisibilityTypeSelected = React.useCallback(
     () => setVisibilityType('secret'),
     [],
   );
 
   const onAnnouncementSelected = React.useCallback(
     () => setAnnouncement(!announcement),
     [announcement],
   );
 
   const toggleUserSelection = React.useCallback((userID: string) => {
     setSelectedUsers((users: $ReadOnlySet<string>) => {
       const newUsers = new Set(users);
       if (newUsers.has(userID)) {
         newUsers.delete(userID);
       } else {
         newUsers.add(userID);
       }
       return newUsers;
     });
   }, []);
 
   const subchannelSettings = React.useMemo(
     () => (
       <SubchannelSettings
         channelName={channelName}
         visibilityType={visibilityType}
         announcement={announcement}
         onChangeChannelName={onChangeChannelName}
         onOpenTypeSelect={onOpenVisibilityTypeSelected}
         onSecretTypeSelect={onSecretVisibilityTypeSelected}
         onAnnouncementSelected={onAnnouncementSelected}
       />
     ),
     [
       channelName,
       visibilityType,
       announcement,
       onChangeChannelName,
       onOpenVisibilityTypeSelected,
       onSecretVisibilityTypeSelected,
       onAnnouncementSelected,
     ],
   );
 
   const stepperButtons = React.useMemo(
     () => ({
       settings: {
         nextProps: {
           content: 'Next',
           disabled: !channelName.trim(),
           onClick: () => {
+            setErrorMessage('');
             setChannelName(channelName.trim());
             setActiveStep('members');
           },
         },
       },
       members: {
         prevProps: {
           content: 'Back',
           onClick: () => setActiveStep('settings'),
         },
         nextProps: {
           content: 'Create',
+          loading: loadingState === 'loading',
+          disabled: selectedUsers.size === 0,
           onClick: () => {
-            // TODO: make form logic
+            dispatchCreateSubchannel();
           },
         },
       },
     }),
-    [channelName],
+    [channelName, dispatchCreateSubchannel, loadingState, selectedUsers],
   );
 
   const subchannelMembers = React.useMemo(
     () => (
       <SubchannelMembers
         parentThreadInfo={parentThreadInfo}
         selectedUsers={selectedUsers}
         searchText={searchUserText}
         setSearchText={setSearchUserText}
         toggleUserSelection={toggleUserSelection}
       />
     ),
     [
       selectedUsers,
       toggleUserSelection,
       parentThreadInfo,
       searchUserText,
       setSearchUserText,
     ],
   );
 
   const modalName =
     activeStep === 'members'
       ? `Create channel - ${trimText(channelName, 11)}`
       : 'Create channel';
 
   return (
     <Modal name={modalName} onClose={onClose} size="fit-content">
       <ComposeSubchannelHeader parentThreadName={parentThreadName} />
       <div className={css.container}>
         <div className={css.stepItem}>
           <Stepper.Container
             className={css.stepContainer}
             activeStep={activeStep}
           >
             <Stepper.Item
               content={subchannelSettings}
               name="settings"
               nextProps={stepperButtons.settings.nextProps}
             />
             <Stepper.Item
               content={subchannelMembers}
               name="members"
               prevProps={stepperButtons.members.prevProps}
               nextProps={stepperButtons.members.nextProps}
+              errorMessage={errorMessage}
             />
           </Stepper.Container>
         </div>
       </div>
     </Modal>
   );
 }
 
 export default ComposeSubchannelModal;