diff --git a/adminapp/src/api.js b/adminapp/src/api.js
index 6cef54e7..323a542a 100644
--- a/adminapp/src/api.js
+++ b/adminapp/src/api.js
@@ -199,6 +199,8 @@ export default {
     post(`/adminapi/v1/marketing_lists/${id}/destroy`, data, ...args),
   rebuildMarketingList: ({ id, ...data }, ...args) =>
     post(`/adminapi/v1/marketing_lists/${id}/rebuild`, data, ...args),
+  uploadingMarketingListCsv: ({ id, ...data }, ...args) =>
+    postForm(`/adminapi/v1/marketing_lists/${id}/upload_csv`, data, ...args),
 
   getMarketingSmsBroadcasts: (data, ...args) =>
     get(`/adminapi/v1/marketing_sms_broadcasts`, data, ...args),
diff --git a/adminapp/src/components/FileUploadInput.jsx b/adminapp/src/components/FileUploadInput.jsx
new file mode 100644
index 00000000..9795b173
--- /dev/null
+++ b/adminapp/src/components/FileUploadInput.jsx
@@ -0,0 +1,56 @@
+import useErrorSnackbar from "../hooks/useErrorSnackbar";
+import useToggle from "../shared/react/useToggle";
+import UploadFileIcon from "@mui/icons-material/UploadFile";
+import { Button, CircularProgress } from "@mui/material";
+import ButtonGroup from "@mui/material/ButtonGroup";
+import { useSnackbar } from "notistack";
+import React from "react";
+
+export default function FileUploadInput({ accept, label, onUpload }) {
+  label = label || "Choose File";
+  accept = accept || "*.*";
+  const [file, setFile] = React.useState("");
+  const uploading = useToggle();
+  const { enqueueErrorSnackbar } = useErrorSnackbar();
+  const { enqueueSnackbar } = useSnackbar();
+
+  function handleFileChange(e) {
+    setFile(e.target.files?.[0] ?? null);
+  }
+
+  async function handleUpload(e) {
+    e.preventDefault();
+    if (!file) {
+      return;
+    }
+    uploading.turnOn();
+
+    try {
+      await onUpload(file);
+      enqueueSnackbar(`Uploaded ${file.name}`, { variant: "success" });
+      setFile(null);
+    } catch (err) {
+      enqueueErrorSnackbar(err);
+    } finally {
+      uploading.turnOff();
+    }
+  }
+
+  return (
+    <ButtonGroup variant="outlined">
+      <Button component="label" variant="outlined">
+        {file ? file.name : label}
+        <input type="file" accept={accept || "*.*"} hidden onChange={handleFileChange} />
+      </Button>
+
+      <Button
+        aria-label="Upload"
+        variant="contained"
+        disabled={!file || uploading.isOn}
+        onClick={handleUpload}
+      >
+        {uploading.isOn ? <CircularProgress size={20} /> : <UploadFileIcon />}
+      </Button>
+    </ButtonGroup>
+  );
+}
diff --git a/adminapp/src/pages/MarketingListDetailPage.jsx b/adminapp/src/pages/MarketingListDetailPage.jsx
index d4a1a3d0..08ccea3b 100644
--- a/adminapp/src/pages/MarketingListDetailPage.jsx
+++ b/adminapp/src/pages/MarketingListDetailPage.jsx
@@ -1,5 +1,6 @@
 import api from "../api";
 import AdminLink from "../components/AdminLink";
+import FileUploadInput from "../components/FileUploadInput";
 import RelatedListRemote from "../components/RelatedListRemote";
 import ResourceDetail from "../components/ResourceDetail";
 import resourceDetailCommonFields from "../components/resourceDetailCommonFields";
@@ -25,6 +26,14 @@ export default function MarketingListDetailPage() {
       .finally(notBusy);
   }
 
+  function handleCsvUpload(file, setModel) {
+    busy();
+    api
+      .uploadingMarketingListCsv({ id, file })
+      .then((r) => setModel(r.data))
+      .finally(notBusy);
+  }
+
   if (isBusy) {
     return <CircularProgress />;
   }
@@ -49,6 +58,11 @@ export default function MarketingListDetailPage() {
       ]}
     >
       {(model, setModel) => [
+        <FileUploadInput
+          accept=".csv"
+          label="Choose ID/Name/Email CSV"
+          onUpload={(f) => handleCsvUpload(f, setModel)}
+        />,
         model.managed && (
           <div>
             <Button
diff --git a/lib/suma/admin_api/marketing_lists.rb b/lib/suma/admin_api/marketing_lists.rb
index 6afdad99..d826053f 100644
--- a/lib/suma/admin_api/marketing_lists.rb
+++ b/lib/suma/admin_api/marketing_lists.rb
@@ -13,6 +13,16 @@ class DetailedListEntity < MarketingListEntity
     expose_related :sms_broadcasts, with: MarketingSmsBroadcastEntity
   end
 
+  helpers do
+    def must_be_unmanaged!(m)
+      adminerror!(403, "Managed lists cannot be edited", code: "marketing_list_managed") if m.managed?
+    end
+
+    def must_be_managed!(m)
+      adminerror!(403, "Only managed lists can be rebuilt", code: "marketing_list_unmanaged") unless m.managed?
+    end
+  end
+
   resource :marketing_lists do
     Suma::AdminAPI::CommonEndpoints.list(
       self,
@@ -41,7 +51,7 @@ class DetailedListEntity < MarketingListEntity
       Suma::Marketing::List,
       DetailedListEntity,
       around: lambda do |rt, m, &block|
-        rt.adminerror!(403, "Managed lists cannot be edited", code: "marketing_list_managed") if m.managed?
+        rt.must_be_unmanaged!(m)
         members = rt.params.delete(:members)
         block.call
         m.member_pks = members.map { |l| l.fetch(:id) } if
@@ -70,8 +80,7 @@ def lookup
       post :rebuild do
         check_admin_role_access!(:read, :marketing_sms)
         list = lookup
-        sleep(1)
-        adminerror!(403, "Only managed lists can be rebuilt", code: "marketing_list_unmanaged") unless list.managed
+        must_be_managed!(list)
         spec = Suma::Marketing::List::Specification.gather_all.find { |spec| spec.full_label == list.label }
         if spec.nil?
           msg = "Could not find a list specification- this list should be unmanaged, please alert a developer"
@@ -82,6 +91,19 @@ def lookup
         status 200
         present list, with: DetailedListEntity
       end
+
+      params do
+        requires :file, type: File
+      end
+      post :upload_csv do
+        check_admin_role_access!(:write, :marketing_sms)
+        list = lookup
+        must_be_unmanaged!(list)
+        csv = params[:file].fetch(:tempfile).read
+        list.update_from_csv(csv)
+        status 200
+        present list, with: DetailedListEntity
+      end
     end
   end
 end
diff --git a/lib/suma/marketing/list.rb b/lib/suma/marketing/list.rb
index 27870267..2393cc3d 100644
--- a/lib/suma/marketing/list.rb
+++ b/lib/suma/marketing/list.rb
@@ -55,6 +55,39 @@ def rebuild_all(*specs)
 
   def managed? = self.managed
 
+  # Given a CSV string, treat each cell as an ID, phone, or email.
+  # Add any members we find to the list.
+  def update_from_csv(txt)
+    csv = CSV.parse(txt)
+    ids = []
+    emails = []
+    phones = []
+    csv.each do |row|
+      row.each do |cell|
+        next if cell.blank?
+        cell = cell.strip
+        if cell.include?("@")
+          emails << cell
+        else
+          ids << cell.to_i if /^\d+$/.match?(cell)
+          if (norm = Suma::PhoneNumber::US.normalize_valid(cell))
+            phones << norm
+          end
+        end
+      end
+    end
+    ds = self.db[:members].where(Sequel[id: ids] | Sequel[email: emails] | Sequel[phone: phones])
+    ds = ds.exclude(id: self.members_dataset.select(:id))
+
+    self.db[:marketing_lists_members].
+      import(
+        [:marketing_list_id, :member_id],
+        ds.select(Sequel.as(self.id, :marketing_list_id), Sequel[:id].as(:member_id)),
+      )
+
+    self.refresh
+  end
+
   def rel_admin_link = "/marketing-list/#{self.id}"
 
   def hybrid_search_fields
diff --git a/lib/suma/phone_number.rb b/lib/suma/phone_number.rb
index 9ea806e6..e1d2dd5f 100644
--- a/lib/suma/phone_number.rb
+++ b/lib/suma/phone_number.rb
@@ -6,17 +6,27 @@ class BadFormat < StandardError; end
   class US
     REGEXP = /^1[0-9]{10}$/
 
+    # Normalize s. May not be valid.
     def self.normalize(s)
       norm = Phony.normalize(s, cc: "1")
       norm = "1#{norm}" if norm.length == 10 && norm.first == "1"
       return norm
     end
 
+    # Return the normalized version of s if valid, nil if invalid.
+    def self.normalize_valid(s)
+      norm = self.normalize(s)
+      return norm if self.valid_normalized?(norm)
+      return nil
+    end
+
+    # Return true if s is valid once normalized.
     def self.valid?(s)
       return false if s.nil?
       return self.valid_normalized?(self.normalize(s))
     end
 
+    # Return true if s is a valid normalized number.
     def self.valid_normalized?(s)
       return REGEXP.match?(s)
     end
diff --git a/lib/suma/spec_helpers/service.rb b/lib/suma/spec_helpers/service.rb
index 5ce2796f..4442c9a2 100644
--- a/lib/suma/spec_helpers/service.rb
+++ b/lib/suma/spec_helpers/service.rb
@@ -415,5 +415,9 @@ def make_json_request(env, params)
       j = Yajl::Encoder.encode(params)
       return env, j
     end
+
+    def in_memory_rack_file(str, content_type="text/plain", binary: false, filename: "inmemory")
+      return Rack::Test::UploadedFile.new(StringIO.new(str), content_type, binary, original_filename: filename)
+    end
   end
 end
diff --git a/spec/suma/admin_api/marketing_lists_spec.rb b/spec/suma/admin_api/marketing_lists_spec.rb
index 59283c0c..e19785ca 100644
--- a/spec/suma/admin_api/marketing_lists_spec.rb
+++ b/spec/suma/admin_api/marketing_lists_spec.rb
@@ -144,4 +144,33 @@ def make_item(i)
       expect(last_response).to have_json_body.that_includes(error: include(code: "marketing_list_spec_missing"))
     end
   end
+
+  describe "POST /v1/marketing_lists/:id/upload_csv" do
+    it "updates the members" do
+      m1 = Suma::Fixtures.member.create(phone: "15552223333")
+      m2 = Suma::Fixtures.member.create(email: "a@b.c")
+      m3 = Suma::Fixtures.member.create
+
+      csv_str = "#{m1.us_phone},#{m2.email}\n#{m3.id},garbage\n000,x@y.z\n"
+      attachment = in_memory_rack_file(csv_str, "text/csv")
+
+      o = Suma::Fixtures.marketing_list.create
+
+      post "/v1/marketing_lists/#{o.id}/upload_csv", file: attachment
+
+      expect(last_response).to have_status(200)
+      expect(o.members).to have_same_ids_as(m1, m2, m3)
+    end
+
+    it "errors if the list is managed" do
+      attachment = in_memory_rack_file("", "text/csv")
+
+      o = Suma::Fixtures.marketing_list.create(managed: true)
+
+      post "/v1/marketing_lists/#{o.id}/upload_csv", file: attachment
+
+      expect(last_response).to have_status(403)
+      expect(last_response).to have_json_body.that_includes(error: include(code: "marketing_list_managed"))
+    end
+  end
 end
diff --git a/spec/suma/marketing/list_spec.rb b/spec/suma/marketing/list_spec.rb
index 74c857df..5ca4cc0c 100644
--- a/spec/suma/marketing/list_spec.rb
+++ b/spec/suma/marketing/list_spec.rb
@@ -141,4 +141,26 @@
       expect(list.members).to contain_exactly(be === member1, be === member3)
     end
   end
+
+  describe "update_from_csv" do
+    it "adds members based on their phone, email, or id" do
+      list = Suma::Fixtures.marketing_list.create
+      existing = Suma::Fixtures.member.create
+      m2 = Suma::Fixtures.member.create
+      m3 = Suma::Fixtures.member.create
+      m4 = Suma::Fixtures.member.create
+      m5 = Suma::Fixtures.member.create
+      _not_on_list = Suma::Fixtures.member.create
+
+      list.add_member(existing)
+      csv = <<~CSV
+        #{m2.id} ,  #{m3.phone}  ,  #{m4.email}
+        #{m5.us_phone}  ,00,a@b.z
+        999-999-999999,,33-33
+      CSV
+
+      list.update_from_csv(csv)
+      expect(list.members).to have_same_ids_as(existing, m2, m3, m4, m5)
+    end
+  end
 end
diff --git a/spec/suma/phone_number_spec.rb b/spec/suma/phone_number_spec.rb
index 6e09b27f..74c46bff 100644
--- a/spec/suma/phone_number_spec.rb
+++ b/spec/suma/phone_number_spec.rb
@@ -11,6 +11,18 @@
       expect { described_class.format("3334445555") }.to raise_error(Suma::PhoneNumber::BadFormat)
       expect(described_class.format?("3334445555")).to be_nil
     end
+
+    it "handles normalization and validity" do
+      expect(described_class.normalize("333")).to eq("1333")
+      expect(described_class.normalize("3334445555")).to eq("13334445555")
+      expect(described_class.normalize_valid("333")).to be_nil
+      expect(described_class.normalize_valid("3334445555")).to eq("13334445555")
+      expect(described_class.valid?("333")).to be(false)
+      expect(described_class.valid?("3334445555")).to be(true)
+      expect(described_class.valid_normalized?("333")).to be(false)
+      expect(described_class.valid_normalized?("3334445555")).to be(false)
+      expect(described_class.valid_normalized?("13334445555")).to be(true)
+    end
   end
 
   describe "format_e164" do