diff --git a/documentation/source/testsAndInProgress/midi.ipynb b/documentation/source/testsAndInProgress/midi.ipynb
index 282d7288a..6768af826 100644
--- a/documentation/source/testsAndInProgress/midi.ipynb
+++ b/documentation/source/testsAndInProgress/midi.ipynb
@@ -13,12 +13,12 @@
    "id": "f380fcf0-4e6a-4d90-a9c6-70b4fa398eea",
    "metadata": {},
    "source": [
-    "MIDI will only play from **Trusted** notebooks."
+    "MIDI will only reliably play from **Trusted** notebooks."
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 1,
+   "execution_count": 4,
    "id": "72e204b7-409b-48ef-b404-a310d281b54c",
    "metadata": {},
    "outputs": [],
@@ -28,7 +28,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 2,
+   "execution_count": 5,
    "id": "c9b77464-389f-4dba-9ac8-aef5bd85e2e1",
    "metadata": {},
    "outputs": [],
@@ -38,7 +38,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 3,
+   "execution_count": 6,
    "id": "e0040c55-5bab-42f8-ad1c-284ea8170647",
    "metadata": {},
    "outputs": [
@@ -46,7 +46,7 @@
      "data": {
       "text/html": [
        "\n",
-       "        <div id=\"midiPlayerDiv98\">\n",
+       "        <div id=\"midiPlayerDiv197\">\n",
        "            <p class=\"m21-trust-warning\">\n",
        "                This MIDI player only runs in <em>trusted</em> notebooks.\n",
        "                In JupyterLab: File &rarr; Trust Notebook, then re-run this cell.\n",
@@ -54,7 +54,7 @@
        "        </div>\n",
        "        <script>\n",
        "        (function() {\n",
-       "            const outputId = \"midiPlayerDiv98\";\n",
+       "            const outputId = \"midiPlayerDiv197\";\n",
        "            const b64 = \"TVRoZAAAAAYAAQACJ2BNVHJrAAAAFAD/UQMHoSAA/1gEBAIYCM5g/y8ATVRyawAAADIA/wMAAOAAQM5gkDxazmCAPAAAkD5azmCAPgAAkEBazmCAQAAAkEFazmCAQQDOYP8vAA==\";\n",
        "            const jsUrl = \"https://cdn.jsdelivr.net/npm/music21j@0.23.1/releases/music21.debug.min.js\";\n",
        "            const cssUrl = \"https://cdn.jsdelivr.net/npm/music21j@0.23.1/releases/music21j.min.css\";\n",
@@ -145,7 +145,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.13.3"
+   "version": "3.14.2"
   }
  },
  "nbformat": 4,
diff --git a/music21/alpha/__init__.py b/music21/alpha/__init__.py
index 47fd99cbc..399df65a2 100644
--- a/music21/alpha/__init__.py
+++ b/music21/alpha/__init__.py
@@ -15,8 +15,8 @@
 The alpha module/directory contains features that are useful for some things, but
 not a core part of the system.  Some of these modules may require external
 libraries that are obscure and not part of the recommended "additional music21
-features" set. (For instance, alpha.chant requires Gregorio and LaTeX -- a daunting
-requirement)
+features" set. (For instance, at one point alpha.chant required
+Gregorio and LaTeX -- a daunting requirement)
 
 This directory is a compromise between removing the features altogether and
 putting them in the main documentation.  Some of these features may "graduate"
diff --git a/music21/common/misc.py b/music21/common/misc.py
index 88c93dd08..fcd773f05 100644
--- a/music21/common/misc.py
+++ b/music21/common/misc.py
@@ -38,6 +38,8 @@
     'unique',
 ]
 
+from functools import cache
+
 if t.TYPE_CHECKING:
     _T = t.TypeVar('_T')
 
@@ -209,22 +211,33 @@ def pitchList(pitchL):
     return '[' + ', '.join([x.nameWithOctave for x in pitchL]) + ']'
 
 
+@cache
 def runningInNotebook() -> bool:
     '''
     return bool if we are running under Jupyter Notebook (not IPython terminal)
-    or Google Colabatory (colab).
+    or Google Colabatory (colab) or Marimo.
 
     Methods based on:
 
     https://stackoverflow.com/questions/15411967/how-can-i-check-if-code-is-executed-in-the-ipython-notebook
-
     (No tests provided here, since results will differ depending on environment)
     '''
-    if sys.stderr.__class__.__name__ == 'OutStream':
+    if runningInJupyterOrColab():
+        return True
+    elif runningInMarimo():
         return True
     else:
         return False
 
+def runningInJupyterOrColab() -> bool:
+    return sys.stderr.__class__.__name__ == 'OutStream'
+
+def runningInMarimo() -> bool:
+    if 'marimo' not in sys.modules:  # only True if it's been loaded already
+        return False
+    # so this is very fast, even if False.
+    return __import__('marimo').running_in_notebook()
+
 
 # ----------------------------
 # match collections, defaultdict()
diff --git a/music21/converter/subConverters.py b/music21/converter/subConverters.py
index 51734f6ab..dccd28020 100644
--- a/music21/converter/subConverters.py
+++ b/music21/converter/subConverters.py
@@ -216,7 +216,7 @@ def show(
         app=None,
         subformats=(),
         **keywords
-    ) -> None:
+    ) -> t.Any|None:
         '''
         Write the data, then show the generated data, using `.launch()` or printing
         to a console.
@@ -355,7 +355,7 @@ class ConverterIPython(SubConverter):
     registerOutputSubformatExtensions = {'lilypond': 'ly'}
 
     def show(self, obj, fmt, app=None, subformats=(),
-             **keywords):  # pragma: no cover
+             **keywords) -> t.Any:  # pragma: no cover
         '''
         show a specialized for Jupyter Notebook using the appropriate subformat.
 
@@ -387,10 +387,11 @@ def show(self, obj, fmt, app=None, subformats=(),
                 subformats=helperSubformats,
                 **keywords,
             )
+            return None
         elif helperFormat == 'midi':
             if t.TYPE_CHECKING:
                 assert isinstance(helperSubConverter, ConverterMidi)
-            ip21_converters.displayMusic21jMIDI(
+            return ip21_converters.displayMusic21jMIDI(
                 obj,
                 subConverter=helperSubConverter,
                 fmt=helperFormat,
diff --git a/music21/ipython21/converters.py b/music21/ipython21/converters.py
index 5c5aaeeb1..859656cf4 100644
--- a/music21/ipython21/converters.py
+++ b/music21/ipython21/converters.py
@@ -18,6 +18,7 @@
 import typing as t
 
 from music21 import common
+from music21.common.misc import runningInJupyterOrColab, runningInMarimo
 from music21.converter import museScore
 from music21 import defaults
 from music21 import environment
@@ -128,10 +129,7 @@ def displayMusic21jMIDI(
     fmt: str = 'midi',
     subformats: Sequence[str] = (),
     **keywords,
-):
-    # noinspection PyPackageRequirements
-    from IPython.display import display, HTML  # type: ignore
-
+) -> t.Any:
     fp = subConverter.write(
         obj,
         fmt,
@@ -141,14 +139,34 @@ def displayMusic21jMIDI(
     )
 
     with open(fp, 'rb') as f:
-        binaryMidiData = f.read()
+        binaryMidiData: bytes = f.read()
+
+    htmlOutput = htmlOutputForMidi(binaryMidiData)
+    displayMusic21jMIDIMarimo(htmlOutput)
+
+    if runningInJupyterOrColab():
+        displayMusic21jMIDIJupyter(htmlOutput)
+    elif runningInMarimo():
+        return displayMusic21jMIDIMarimo(htmlOutput)
+    else:
+        raise ValueError('Cannot run displayMusic21jMIDI if not running in a supported Notebook')
+
+def displayMusic21jMIDIJupyter(htmlOutput: str) -> None:
+    from IPython.display import display, HTML
+    display(HTML(htmlOutput))
+
+def displayMusic21jMIDIMarimo(htmlOutput: str) -> t.Any:
+    # noinspection PyPackageRequirements
+    from marimo import iframe  # type: ignore  # pylint: disable=import-error
+    return iframe(htmlOutput, width='100%', height='80px')
 
+def htmlOutputForMidi(binaryMidiData: bytes) -> str:
     binaryBase64 = base64.b64encode(binaryMidiData)
     s = common.SingletonCounter()
     outputId = 'midiPlayerDiv' + str(s())
     utf_binary: str = binaryBase64.decode('utf-8')
     # noinspection PyTypeChecker
-    display(HTML('''
+    return '''
         <div id="''' + outputId + '''">
             <p class="m21-trust-warning">
                 This MIDI player only runs in <em>trusted</em> notebooks.
@@ -209,7 +227,7 @@ def displayMusic21jMIDI(
             }
             script.addEventListener("load", function() { play(window.music21); });
         })();
-        </script>'''))
+        </script>'''
 
 
     # def vfshow(self, s):