diff --git a/nucleus/rna/admin.py b/nucleus/rna/admin.py
index 7fb096ca..5f3fdc68 100644
--- a/nucleus/rna/admin.py
+++ b/nucleus/rna/admin.py
@@ -32,7 +32,7 @@ class Meta:
 
 class NoteAdmin(admin.ModelAdmin):
     form = NoteAdminForm
-    filter_horizontal = ["releases"]
+    filter_horizontal = ["releases", "relevant_countries"]
     list_display = ("id", "bug", "tag", "note", "created")
     list_display_links = ("id",)
     list_filter = ("tag", "is_known_issue", "releases__product", "releases__version", "progressive_rollout")
@@ -148,5 +148,13 @@ def set_to_private(self, request, queryset):
             obj.save()
 
 
+class CountryAdmin(admin.ModelAdmin):
+    search_fields = ("name", "code")
+
+    class Meta:
+        model = models.Country
+
+
+admin.site.register(models.Country, CountryAdmin)
 admin.site.register(models.Note, NoteAdmin)
 admin.site.register(models.Release, ReleaseAdmin)
diff --git a/nucleus/rna/migrations/0008_add_country_model.py b/nucleus/rna/migrations/0008_add_country_model.py
new file mode 100644
index 00000000..457d2a79
--- /dev/null
+++ b/nucleus/rna/migrations/0008_add_country_model.py
@@ -0,0 +1,28 @@
+# Generated by Django 3.2.23 on 2023-11-23 13:24
+
+from django.db import migrations, models
+
+import django_extensions.db.fields
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("rna", "0007_release_reviewed_by_release_manager"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="Country",
+            fields=[
+                ("id", models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
+                ("created", django_extensions.db.fields.CreationDateTimeField(auto_now_add=True)),
+                ("modified", models.DateTimeField(blank=True, db_index=True, editable=False)),
+                ("name", models.CharField(max_length=128)),
+                ("code", models.CharField(help_text="3166-1-alpha-2 code", max_length=2)),
+            ],
+        ),
+        migrations.AddConstraint(
+            model_name="country",
+            constraint=models.UniqueConstraint(fields=("name", "code"), name="unique_country_name_for_code"),
+        ),
+    ]
diff --git a/nucleus/rna/migrations/0009_data_bootstrap_countries_and_codes.py b/nucleus/rna/migrations/0009_data_bootstrap_countries_and_codes.py
new file mode 100644
index 00000000..5157c7e8
--- /dev/null
+++ b/nucleus/rna/migrations/0009_data_bootstrap_countries_and_codes.py
@@ -0,0 +1,279 @@
+# Generated by Django 3.2.23 on 2023-11-23 13:24
+
+from django.db import migrations
+from django.utils.timezone import now
+
+iso_3166_1_alpha_2_country_codes = (
+    # Source https://datahub.io/core/country-list
+    # Public domain license: https://opendatacommons.org/licenses/pddl/
+    ("Afghanistan", "AF"),
+    ("Åland Islands", "AX"),
+    ("Albania", "AL"),
+    ("Algeria", "DZ"),
+    ("American Samoa", "AS"),
+    ("Andorra", "AD"),
+    ("Angola", "AO"),
+    ("Anguilla", "AI"),
+    ("Antarctica", "AQ"),
+    ("Antigua and Barbuda", "AG"),
+    ("Argentina", "AR"),
+    ("Armenia", "AM"),
+    ("Aruba", "AW"),
+    ("Australia", "AU"),
+    ("Austria", "AT"),
+    ("Azerbaijan", "AZ"),
+    ("Bahamas", "BS"),
+    ("Bahrain", "BH"),
+    ("Bangladesh", "BD"),
+    ("Barbados", "BB"),
+    ("Belarus", "BY"),
+    ("Belgium", "BE"),
+    ("Belize", "BZ"),
+    ("Benin", "BJ"),
+    ("Bermuda", "BM"),
+    ("Bhutan", "BT"),
+    ("Bolivia, Plurinational State of", "BO"),
+    ("Bonaire, Sint Eustatius and Saba", "BQ"),
+    ("Bosnia and Herzegovina", "BA"),
+    ("Botswana", "BW"),
+    ("Bouvet Island", "BV"),
+    ("Brazil", "BR"),
+    ("British Indian Ocean Territory", "IO"),
+    ("Brunei Darussalam", "BN"),
+    ("Bulgaria", "BG"),
+    ("Burkina Faso", "BF"),
+    ("Burundi", "BI"),
+    ("Cambodia", "KH"),
+    ("Cameroon", "CM"),
+    ("Canada", "CA"),
+    ("Cape Verde", "CV"),
+    ("Cayman Islands", "KY"),
+    ("Central African Republic", "CF"),
+    ("Chad", "TD"),
+    ("Chile", "CL"),
+    ("China", "CN"),
+    ("Christmas Island", "CX"),
+    ("Cocos (Keeling) Islands", "CC"),
+    ("Colombia", "CO"),
+    ("Comoros", "KM"),
+    ("Congo", "CG"),
+    ("Congo, the Democratic Republic of the", "CD"),
+    ("Cook Islands", "CK"),
+    ("Costa Rica", "CR"),
+    ("Côte d'Ivoire", "CI"),
+    ("Croatia", "HR"),
+    ("Cuba", "CU"),
+    ("Curaçao", "CW"),
+    ("Cyprus", "CY"),
+    ("Czech Republic", "CZ"),
+    ("Denmark", "DK"),
+    ("Djibouti", "DJ"),
+    ("Dominica", "DM"),
+    ("Dominican Republic", "DO"),
+    ("Ecuador", "EC"),
+    ("Egypt", "EG"),
+    ("El Salvador", "SV"),
+    ("Equatorial Guinea", "GQ"),
+    ("Eritrea", "ER"),
+    ("Estonia", "EE"),
+    ("Ethiopia", "ET"),
+    ("Falkland Islands (Malvinas)", "FK"),
+    ("Faroe Islands", "FO"),
+    ("Fiji", "FJ"),
+    ("Finland", "FI"),
+    ("France", "FR"),
+    ("French Guiana", "GF"),
+    ("French Polynesia", "PF"),
+    ("French Southern Territories", "TF"),
+    ("Gabon", "GA"),
+    ("Gambia", "GM"),
+    ("Georgia", "GE"),
+    ("Germany", "DE"),
+    ("Ghana", "GH"),
+    ("Gibraltar", "GI"),
+    ("Greece", "GR"),
+    ("Greenland", "GL"),
+    ("Grenada", "GD"),
+    ("Guadeloupe", "GP"),
+    ("Guam", "GU"),
+    ("Guatemala", "GT"),
+    ("Guernsey", "GG"),
+    ("Guinea", "GN"),
+    ("Guinea-Bissau", "GW"),
+    ("Guyana", "GY"),
+    ("Haiti", "HT"),
+    ("Heard Island and McDonald Islands", "HM"),
+    ("Holy See (Vatican City State)", "VA"),
+    ("Honduras", "HN"),
+    ("Hong Kong", "HK"),
+    ("Hungary", "HU"),
+    ("Iceland", "IS"),
+    ("India", "IN"),
+    ("Indonesia", "ID"),
+    ("Iran, Islamic Republic of", "IR"),
+    ("Iraq", "IQ"),
+    ("Ireland", "IE"),
+    ("Isle of Man", "IM"),
+    ("Israel", "IL"),
+    ("Italy", "IT"),
+    ("Jamaica", "JM"),
+    ("Japan", "JP"),
+    ("Jersey", "JE"),
+    ("Jordan", "JO"),
+    ("Kazakhstan", "KZ"),
+    ("Kenya", "KE"),
+    ("Kiribati", "KI"),
+    ("Korea, Democratic People's Republic of", "KP"),
+    ("Korea, Republic of", "KR"),
+    ("Kuwait", "KW"),
+    ("Kyrgyzstan", "KG"),
+    ("Lao People's Democratic Republic", "LA"),
+    ("Latvia", "LV"),
+    ("Lebanon", "LB"),
+    ("Lesotho", "LS"),
+    ("Liberia", "LR"),
+    ("Libya", "LY"),
+    ("Liechtenstein", "LI"),
+    ("Lithuania", "LT"),
+    ("Luxembourg", "LU"),
+    ("Macao", "MO"),
+    ("Macedonia, the Former Yugoslav Republic of", "MK"),
+    ("Madagascar", "MG"),
+    ("Malawi", "MW"),
+    ("Malaysia", "MY"),
+    ("Maldives", "MV"),
+    ("Mali", "ML"),
+    ("Malta", "MT"),
+    ("Marshall Islands", "MH"),
+    ("Martinique", "MQ"),
+    ("Mauritania", "MR"),
+    ("Mauritius", "MU"),
+    ("Mayotte", "YT"),
+    ("Mexico", "MX"),
+    ("Micronesia, Federated States of", "FM"),
+    ("Moldova, Republic of", "MD"),
+    ("Monaco", "MC"),
+    ("Mongolia", "MN"),
+    ("Montenegro", "ME"),
+    ("Montserrat", "MS"),
+    ("Morocco", "MA"),
+    ("Mozambique", "MZ"),
+    ("Myanmar", "MM"),
+    ("Namibia", "NA"),
+    ("Nauru", "NR"),
+    ("Nepal", "NP"),
+    ("Netherlands", "NL"),
+    ("New Caledonia", "NC"),
+    ("New Zealand", "NZ"),
+    ("Nicaragua", "NI"),
+    ("Niger", "NE"),
+    ("Nigeria", "NG"),
+    ("Niue", "NU"),
+    ("Norfolk Island", "NF"),
+    ("Northern Mariana Islands", "MP"),
+    ("Norway", "NO"),
+    ("Oman", "OM"),
+    ("Pakistan", "PK"),
+    ("Palau", "PW"),
+    ("Palestine, State of", "PS"),
+    ("Panama", "PA"),
+    ("Papua New Guinea", "PG"),
+    ("Paraguay", "PY"),
+    ("Peru", "PE"),
+    ("Philippines", "PH"),
+    ("Pitcairn", "PN"),
+    ("Poland", "PL"),
+    ("Portugal", "PT"),
+    ("Puerto Rico", "PR"),
+    ("Qatar", "QA"),
+    ("Réunion", "RE"),
+    ("Romania", "RO"),
+    ("Russian Federation", "RU"),
+    ("Rwanda", "RW"),
+    ("Saint Barthélemy", "BL"),
+    ("Saint Helena, Ascension and Tristan da Cunha", "SH"),
+    ("Saint Kitts and Nevis", "KN"),
+    ("Saint Lucia", "LC"),
+    ("Saint Martin (French part)", "MF"),
+    ("Saint Pierre and Miquelon", "PM"),
+    ("Saint Vincent and the Grenadines", "VC"),
+    ("Samoa", "WS"),
+    ("San Marino", "SM"),
+    ("Sao Tome and Principe", "ST"),
+    ("Saudi Arabia", "SA"),
+    ("Senegal", "SN"),
+    ("Serbia", "RS"),
+    ("Seychelles", "SC"),
+    ("Sierra Leone", "SL"),
+    ("Singapore", "SG"),
+    ("Sint Maarten (Dutch part)", "SX"),
+    ("Slovakia", "SK"),
+    ("Slovenia", "SI"),
+    ("Solomon Islands", "SB"),
+    ("Somalia", "SO"),
+    ("South Africa", "ZA"),
+    ("South Georgia and the South Sandwich Islands", "GS"),
+    ("South Sudan", "SS"),
+    ("Spain", "ES"),
+    ("Sri Lanka", "LK"),
+    ("Sudan", "SD"),
+    ("Suriname", "SR"),
+    ("Svalbard and Jan Mayen", "SJ"),
+    ("Swaziland", "SZ"),
+    ("Sweden", "SE"),
+    ("Switzerland", "CH"),
+    ("Syrian Arab Republic", "SY"),
+    ("Taiwan, Province of China", "TW"),
+    ("Tajikistan", "TJ"),
+    ("Tanzania, United Republic of", "TZ"),
+    ("Thailand", "TH"),
+    ("Timor-Leste", "TL"),
+    ("Togo", "TG"),
+    ("Tokelau", "TK"),
+    ("Tonga", "TO"),
+    ("Trinidad and Tobago", "TT"),
+    ("Tunisia", "TN"),
+    ("Turkey", "TR"),
+    ("Turkmenistan", "TM"),
+    ("Turks and Caicos Islands", "TC"),
+    ("Tuvalu", "TV"),
+    ("Uganda", "UG"),
+    ("Ukraine", "UA"),
+    ("United Arab Emirates", "AE"),
+    ("United Kingdom", "GB"),
+    ("United States", "US"),
+    ("United States Minor Outlying Islands", "UM"),
+    ("Uruguay", "UY"),
+    ("Uzbekistan", "UZ"),
+    ("Vanuatu", "VU"),
+    ("Venezuela, Bolivarian Republic of", "VE"),
+    ("Viet Nam", "VN"),
+    ("Virgin Islands, British", "VG"),
+    ("Virgin Islands, U.S.", "VI"),
+    ("Wallis and Futuna", "WF"),
+    ("Western Sahara", "EH"),
+    ("Yemen", "YE"),
+    ("Zambia", "ZM"),
+    ("Zimbabwe", "ZW"),
+)
+
+
+def forwards(apps, schema_editor):
+    Country = apps.get_model("rna.Country")
+    for name, code in iso_3166_1_alpha_2_country_codes:
+        Country.objects.create(name=name, code=code, modified=now())
+
+
+def backwards(apps, schema_editor):
+    Country = apps.get_model("rna.Country")
+    Country.objects.all().delete()
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("rna", "0008_add_country_model"),
+    ]
+
+    operations = [
+        migrations.RunPython(forwards, backwards),
+    ]
diff --git a/nucleus/rna/migrations/0010_note_only_applies_to_countries.py b/nucleus/rna/migrations/0010_note_only_applies_to_countries.py
new file mode 100644
index 00000000..d9bdc341
--- /dev/null
+++ b/nucleus/rna/migrations/0010_note_only_applies_to_countries.py
@@ -0,0 +1,25 @@
+# Generated by Django 3.2.23 on 2023-11-23 13:33
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("rna", "0009_data_bootstrap_countries_and_codes"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="note",
+            name="relevant_countries",
+            field=models.ManyToManyField(
+                blank=True,
+                help_text=(
+                    "Select the countries where this Note applies, as part of a "
+                    "progressive rollout. This info will only be shown on the Release "
+                    "page if 'Progressive rollout', above, is ticked."
+                ),
+                to="rna.Country",
+            ),
+        ),
+    ]
diff --git a/nucleus/rna/migrations/0011_alter_country_options.py b/nucleus/rna/migrations/0011_alter_country_options.py
new file mode 100644
index 00000000..7ffecc22
--- /dev/null
+++ b/nucleus/rna/migrations/0011_alter_country_options.py
@@ -0,0 +1,16 @@
+# Generated by Django 3.2.23 on 2023-11-23 13:38
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("rna", "0010_note_only_applies_to_countries"),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name="country",
+            options={"ordering": ["name"], "verbose_name_plural": "Countries"},
+        ),
+    ]
diff --git a/nucleus/rna/models.py b/nucleus/rna/models.py
index 219f63cb..3ae1b935 100644
--- a/nucleus/rna/models.py
+++ b/nucleus/rna/models.py
@@ -6,7 +6,7 @@
 
 from django.conf import settings
 from django.db import models
-from django.db.models import Q
+from django.db.models import Q, UniqueConstraint
 from django.forms.models import model_to_dict
 from django.utils.text import slugify
 from django.utils.timezone import now
@@ -177,6 +177,15 @@ class Note(SaveToGithubModel):
     sort_num = models.IntegerField(default=0)
     is_public = models.BooleanField(default=True)
     progressive_rollout = models.BooleanField(default=False)
+    relevant_countries = models.ManyToManyField(
+        "Country",
+        blank=True,
+        help_text=(
+            "Select the countries where this Note applies, as part of a "
+            "progressive rollout. This info will only be shown on the Release "
+            "page if 'Progressive rollout', above, is ticked."
+        ),
+    )
 
     related_field_to_github = "releases"
 
@@ -201,6 +210,9 @@ def to_dict(self, release=None):
         if release and self.is_known_issue_for(release):
             data["tag"] = "Known"
 
+        if self.relevant_countries.count():
+            data["relevant_countries"] = [x.to_dict() for x in self.relevant_countries.all()]
+
         return data
 
     def __str__(self):
@@ -208,3 +220,35 @@ def __str__(self):
 
     class Meta:
         get_latest_by = "modified"
+
+
+class Country(SaveToGithubModel):
+    # Simple model for associating a Country with a Note
+
+    name = models.CharField(
+        blank=False,
+        max_length=128,
+    )
+    code = models.CharField(
+        blank=False,
+        help_text="3166-1-alpha-2 code",
+        max_length=2,
+    )
+
+    def __str__(self):
+        return f"{self.name} ({self.code})"
+
+    class Meta:
+        verbose_name_plural = "Countries"
+        ordering = ["name"]
+        constraints = [
+            UniqueConstraint(
+                fields=["name", "code"],
+                name="unique_country_name_for_code",
+            ),
+        ]
+
+    def to_dict(self):
+        data = model_to_dict(self)
+        del data["id"]  # no need to dump out the internal ID for a Country
+        return data
diff --git a/nucleus/rna/serializers.py b/nucleus/rna/serializers.py
index bec98780..0b82a4ac 100644
--- a/nucleus/rna/serializers.py
+++ b/nucleus/rna/serializers.py
@@ -4,7 +4,7 @@
 
 from rest_framework import serializers
 
-from .models import Note, Release
+from .models import Country, Note, Release
 
 
 class HyperlinkedModelSerializerWithPkField(serializers.HyperlinkedModelSerializer):
@@ -14,7 +14,21 @@ def get_default_field_names(self, declared_fields, model_info):
         return fields
 
 
+class CountrySerializer(serializers.ModelSerializer):
+    class Meta:
+        model = Country
+        fields = [
+            "name",
+            "code",
+        ]
+
+
 class NoteSerializer(HyperlinkedModelSerializerWithPkField):
+    relevant_countries = CountrySerializer(
+        read_only=True,
+        many=True,
+    )
+
     class Meta:
         model = Note
         fields = "__all__"
diff --git a/nucleus/rna/tests/test_models.py b/nucleus/rna/tests/test_models.py
index 182cb653..9e9e0679 100644
--- a/nucleus/rna/tests/test_models.py
+++ b/nucleus/rna/tests/test_models.py
@@ -3,7 +3,7 @@
 from django.test import TestCase
 from django.utils.timezone import now
 
-from nucleus.rna.models import Note, Release
+from nucleus.rna.models import Country, Note, Release
 
 
 class TestReleaseQueries(TestCase):
@@ -103,3 +103,35 @@ def test_to_dict__simple__no_relations(self):
 
         assert "created" in dumped_dict
         assert "modified" in dumped_dict
+
+    def test_to_dict__relevant_country_field(self):
+        # Country data is bootstrapped by a data migration
+
+        iceland = Country.objects.get(code="IS")
+        india = Country.objects.get(code="IN")
+
+        data = dict(
+            bug=1234,
+            note="Test note",
+            tag="this is a tag",
+            sort_num=1,
+            is_public=True,
+            progressive_rollout=True,
+        )
+
+        note = Note(**data)
+        note.save()
+
+        assert note.relevant_countries.count() == 0
+        dumped_dict = note.to_dict()
+        assert dumped_dict["relevant_countries"] == []
+
+        note.relevant_countries.add(india)
+        note.relevant_countries.add(iceland)
+        assert note.relevant_countries.count() == 2
+
+        dumped_dict = note.to_dict()
+        assert dumped_dict["relevant_countries"] == [
+            {"name": "Iceland", "code": "IS"},
+            {"name": "India", "code": "IN"},
+        ]