diff --git a/libs/tup-components/src/projects/users/UserList/AddUserModal.module.css b/libs/tup-components/src/projects/users/UserList/AddUserModal.module.css
new file mode 100644
index 000000000..14338521f
--- /dev/null
+++ b/libs/tup-components/src/projects/users/UserList/AddUserModal.module.css
@@ -0,0 +1,32 @@
+/* To prevent dynamic height adjustment */
+.root :global(.modal-content) {
+  height: 50vh;
+}
+
+/* To activate scrolling from SectionTableWrapper contentShouldScroll */
+/* NOTE: I do not think this should be required in client CSS */
+/* HELP: What other solutions exist? If not, then…
+         should SectionTableWrapper apply this? */
+.table-wrap {
+  overflow-y: auto;
+}
+.body {
+  display: grid;
+  grid-template-rows: auto auto 1fr;
+}
+
+.add-remove-column {
+  text-align: right;
+
+  /* To "shrink-wrap" table cell */
+  /* CAVEAT: Requires table `table-layout: auto` (browser default) */
+  width: 1%;
+  white-space: nowrap;
+}
+
+.success-icon  {
+  margin-right: 0.5rem;
+  vertical-align: text-top;
+
+  color: var(--global-color-success--normal);
+}
diff --git a/libs/tup-components/src/projects/users/UserList/AddUserModal.test.tsx b/libs/tup-components/src/projects/users/UserList/AddUserModal.test.tsx
new file mode 100644
index 000000000..25f0e9c8c
--- /dev/null
+++ b/libs/tup-components/src/projects/users/UserList/AddUserModal.test.tsx
@@ -0,0 +1,27 @@
+import AddUserModal from './AddUserModal';
+import { testRender } from '@tacc/tup-testing';
+import { screen, fireEvent, within } from '@testing-library/react';
+
+describe('AddUserModal', () => {
+  it('should display search results', async () => {
+    testRender(<AddUserModal projectId={59184} />);
+    const modalButton = screen.getByRole('button');
+    // open the modal
+    fireEvent.click(modalButton);
+
+    const searchButton = screen.getByText('Search');
+    fireEvent.click(searchButton);
+    const rows = await screen.findAllByRole('row');
+    expect(rows.length).toBe(3);
+
+    // A user in the project should display as added already
+    const existingUserRow = rows[1];
+    const rowQuery = await within(existingUserRow).findByText(/Added/);
+    expect(rowQuery).toBeDefined();
+
+    // A user who is not in the project should display a prompt.
+    const newUserRow = rows[2];
+    const rowQuery2 = await within(newUserRow).findByText(/Add User/);
+    expect(rowQuery2).toBeDefined();
+  });
+});
diff --git a/libs/tup-components/src/projects/users/UserList/AddUserModal.tsx b/libs/tup-components/src/projects/users/UserList/AddUserModal.tsx
new file mode 100644
index 000000000..61271a47b
--- /dev/null
+++ b/libs/tup-components/src/projects/users/UserList/AddUserModal.tsx
@@ -0,0 +1,222 @@
+import {
+  Button,
+  LoadingSpinner,
+  Icon,
+  SectionMessage,
+  SectionTableWrapper,
+} from '@tacc/core-components';
+import { Modal, ModalHeader, ModalBody, ModalFooter } from 'reactstrap';
+import { Input } from 'reactstrap';
+import React, { useState } from 'react';
+import {
+  useUserLookup,
+  UserSearchResult,
+  useProjectUsers,
+  useAddProjectUser,
+  useRemoveProjectUser,
+} from '@tacc/tup-hooks';
+
+import styles from './AddUserModal.module.css';
+import stylesUserList from './UserList.module.css';
+
+type FieldValue = 'email' | 'username' | 'last_name';
+
+const AddUserButton: React.FC<{ username: string; projectId: number }> = ({
+  username,
+  projectId,
+}) => {
+  const { mutate, isLoading } = useAddProjectUser(projectId);
+  if (isLoading) return <LoadingSpinner placement="inline" />;
+  return (
+    <Button type="link" onClick={() => mutate({ username })}>
+      + Add User
+    </Button>
+  );
+};
+
+const RemoveUser: React.FC<{ username: string; projectId: number }> = ({
+  username,
+  projectId,
+}) => {
+  const { mutate, isLoading } = useRemoveProjectUser(projectId, username);
+  if (isLoading)
+    return (
+      <div>
+        <LoadingSpinner placement="inline" />
+      </div>
+    );
+  return (
+    <>
+      <Icon name="approved-reverse" className={styles['success-icon']}></Icon>{' '}
+      Added &nbsp;| &nbsp;
+      <Button type="link" onClick={() => mutate({})}>
+        Remove
+      </Button>
+    </>
+  );
+};
+
+const UserSearchTable: React.FC<{
+  users: UserSearchResult[];
+  projectId: number;
+}> = ({ users, projectId }) => {
+  const { data: projectUsers } = useProjectUsers(projectId);
+
+  const userInProject = (username: string) => {
+    return (projectUsers || []).some((user) => user.username === username);
+  };
+
+  if (!users.length)
+    return (
+      <SectionMessage type="warn">
+        No users matching your query could be found.
+      </SectionMessage>
+    );
+
+  return (
+    <table className="o-fixed-header-table">
+      <thead>
+        <tr>
+          <th>Name</th>
+          <th>Email</th>
+          <th>Username</th>
+          <th className={styles['add-remove-column']}></th>
+        </tr>
+      </thead>
+      <tbody>
+        {users.map((user) => (
+          <tr key={user.username}>
+            <td>{user.name}</td>
+            <td>{user.email}</td>
+            <td>{user.username}</td>
+            <td className={styles['add-remove-column']}>
+              {userInProject(user.username) ? (
+                <RemoveUser projectId={projectId} username={user.username} />
+              ) : (
+                <AddUserButton username={user.username} projectId={projectId} />
+              )}
+            </td>
+          </tr>
+        ))}
+      </tbody>
+    </table>
+  );
+};
+
+const AddUserModal: React.FC<{ projectId: number }> = ({ projectId }) => {
+  const [isOpen, setIsOpen] = useState(false);
+  const toggle = () => {
+    setIsOpen(!isOpen);
+    setField('last_name');
+    setQuery('');
+  };
+
+  const [field, setField] = useState<FieldValue>('last_name');
+  const [query, setQuery] = useState('');
+  const { data, isFetching, refetch } = useUserLookup(projectId, query, field);
+
+  const onSubmit = (e: React.FormEvent) => {
+    e.preventDefault();
+    refetch();
+  };
+
+  const closeBtn = (
+    <button className="close" onClick={toggle} type="button">
+      &times;
+    </button>
+  );
+
+  return (
+    <>
+      <Button onClick={() => toggle()}>+ Add Users</Button>
+      <Modal
+        isOpen={isOpen}
+        toggle={toggle}
+        size="lg"
+        className={`${styles['root']} modal-dialog-centered`}
+      >
+        <ModalHeader toggle={toggle} close={closeBtn}>
+          <span>Add Users</span>
+        </ModalHeader>
+        <ModalBody className={styles['body']}>
+          <h3 style={{ marginBottom: '10px' }}>Search for User</h3>
+          <form onSubmit={(e) => onSubmit(e)}>
+            {/* Radio labels for selecting lastname/email/username for search */}
+            <div className={stylesUserList['radio-group']}>
+              <input
+                name="adduser-field"
+                id="adduser-radio-lastname"
+                type="radio"
+                value="last_name"
+                onChange={(e) => setField(e.target.value as FieldValue)}
+                checked={field === 'last_name'}
+              />
+              <label htmlFor="adduser-radio-lastname">Last Name</label>
+
+              <input
+                name="adduser-field"
+                id="adduser-radio-email"
+                type="radio"
+                value="email"
+                onChange={(e) => setField(e.target.value as FieldValue)}
+                checked={field === 'email'}
+              />
+              <label htmlFor="adduser-radio-email">Email</label>
+
+              <input
+                name="adduser-field"
+                id="adduser-radio-username"
+                type="radio"
+                value="username"
+                onChange={(e) => setField(e.target.value as FieldValue)}
+                checked={field === 'username'}
+              />
+              <label htmlFor="adduser-radio-username">Username</label>
+            </div>
+            {/* Search bar input group */}
+            <div className="input-group">
+              <div className="input-group-prepend">
+                <Button
+                  className={stylesUserList['search-button']}
+                  type="secondary"
+                  iconNameBefore="search"
+                  attr="submit"
+                  isLoading={isFetching}
+                >
+                  Search
+                </Button>
+              </div>
+              <Input
+                style={{ fontSize: '1em' }}
+                id="add-user"
+                value={query}
+                onChange={(e) => setQuery(e.target.value)}
+              />
+            </div>
+            <label
+              className={stylesUserList['search-input-label']}
+              htmlFor="add-user"
+            >
+              <i>Enter their exact name, email address, or username.</i>
+            </label>
+          </form>
+          {/* Search result table */}
+          {data && (
+            <SectionTableWrapper
+              className={styles['table-wrap']}
+              contentShouldScroll
+            >
+              <UserSearchTable
+                users={data}
+                projectId={projectId}
+              ></UserSearchTable>
+            </SectionTableWrapper>
+          )}
+        </ModalBody>
+        <ModalFooter />
+      </Modal>
+    </>
+  );
+};
+
+export default AddUserModal;
diff --git a/libs/tup-components/src/projects/users/UserList/ManageTeam.tsx b/libs/tup-components/src/projects/users/UserList/ManageTeam.tsx
index 898c2cde2..1d2a50cd8 100644
--- a/libs/tup-components/src/projects/users/UserList/ManageTeam.tsx
+++ b/libs/tup-components/src/projects/users/UserList/ManageTeam.tsx
@@ -1,6 +1,7 @@
 import { Button } from '@tacc/core-components';
 import { useProject, useRoleForCurrentUser } from '@tacc/tup-hooks';
 import styles from './UserList.module.css';
+import AddUserModal from './AddUserModal';
 
 const ManageTeam: React.FC<{ projectId: number }> = ({ projectId }) => {
   const currentUserRole = useRoleForCurrentUser(projectId) ?? '';
@@ -25,13 +26,7 @@ const ManageTeam: React.FC<{ projectId: number }> = ({ projectId }) => {
 
   return (
     <div className={styles['user-navactions']}>
-      <a
-        target="_blank"
-        rel="noreferrer"
-        href={`https://accounts.tacc.utexas.edu/project_invite?project_id=${projectId}`}
-      >
-        <Button>+ Add Users</Button>
-      </a>
+      <AddUserModal projectId={projectId} />
     </div>
   );
 };