diff --git a/config/config.yml b/config/config.yml
index 104643c..afc7859 100644
--- a/config/config.yml
+++ b/config/config.yml
@@ -18,5 +18,8 @@ stages:
   - name: Postflight
     class: Postflight
     file: postflight
+  - name: GenerateChecksums
+    class: GenerateChecksums
+    file: generate_checksums
 
 
diff --git a/lib/stage/generate_checksums.rb b/lib/stage/generate_checksums.rb
new file mode 100644
index 0000000..5b01c92
--- /dev/null
+++ b/lib/stage/generate_checksums.rb
@@ -0,0 +1,30 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "stage"
+
+module ChecksumFileGenerator
+  def self.write(path)
+    FileUtils.cd(path) do
+      `md5sum * > checksum.md5`
+    end
+  end
+end
+
+class GenerateChecksums < Stage
+  def run(agenda)
+    @bar.steps = shipment.objid_directories.count
+    shipment.objid_directories.each_with_index do |dir, i|
+      @bar.step! i, dir
+      remove_existing_checksum_file(dir)
+      ChecksumFileGenerator.write(dir)
+    end
+  end
+
+  private
+
+  def remove_existing_checksum_file(dir)
+    checksum_file_path = File.join(dir, "checksum.md5")
+    FileUtils.rm_f(checksum_file_path) if File.exist?(checksum_file_path)
+  end
+end
diff --git a/spec/stage/generate_checksums_spec.rb b/spec/stage/generate_checksums_spec.rb
new file mode 100644
index 0000000..8124424
--- /dev/null
+++ b/spec/stage/generate_checksums_spec.rb
@@ -0,0 +1,44 @@
+describe ChecksumFileGenerator do
+  include_context "uses temp dir"
+  context ".write" do
+    it "writes an checksum.md5 file for files in a given directory" do
+      FileUtils.cp("spec/fixtures/10_10_8_400.jp2", temp_dir_path)
+      described_class.write(temp_dir_path)
+      checksum_contents = File.read(File.join(temp_dir_path, "checksum.md5"))
+      expect(checksum_contents).to include("  10_10_8_400.jp2")
+    end
+  end
+end
+
+describe GenerateChecksums do
+  include_context "uses temp dir"
+  let(:barcode) { "39015002231713" }
+  let(:shipment_path) { "#{temp_dir_path}/test_shipment" }
+  let(:item_path) { "#{shipment_path}/#{barcode}" }
+  let(:shipment) { Shipment.new(shipment_path) }
+  subject do
+    described_class.new(shipment, config: Config.new({no_progress: true}))
+  end
+
+  def set_up_shipment
+    FileUtils.mkdir_p(item_path)
+    FileUtils.cp("spec/fixtures/10_10_8_400.jp2", item_path)
+  end
+
+  it "creates a checksum file" do
+    set_up_shipment
+
+    subject.run!
+    checksum_contents = File.read(File.join(item_path, "checksum.md5"))
+    expect(checksum_contents).to include("  10_10_8_400.jp2")
+  end
+
+  it "original checksum file is removed before calculating checksum" do
+    set_up_shipment
+    FileUtils.touch("#{item_path}/checksum.md5")
+    subject.run!
+    checksum_contents = File.read(File.join(item_path, "checksum.md5"))
+    expect(checksum_contents).to include("  10_10_8_400.jp2")
+    expect(checksum_contents).not_to include("  checksum.md5")
+  end
+end