diff --git a/lib/twine/cli.rb b/lib/twine/cli.rb
index d96cc08..a9b5fff 100644
--- a/lib/twine/cli.rb
+++ b/lib/twine/cli.rb
@@ -89,6 +89,12 @@ module Twine
           end
           options[:output_encoding] = e
         end
+        opts.on('--validate', 'Validate the strings file before formatting it') do
+          options[:validate] = true
+        end
+        opts.on('-p', '--pedantic', 'When validating a strings file, perform additional checks that go beyond pure validity (like presence of tags)') do
+          options[:pedantic] = true
+        end
         opts.on('-h', '--help', 'Show this message.') do |h|
           puts opts.help
           exit
diff --git a/lib/twine/runner.rb b/lib/twine/runner.rb
index f160226..f113a11 100644
--- a/lib/twine/runner.rb
+++ b/lib/twine/runner.rb
@@ -43,6 +43,8 @@ module Twine
     end
 
     def generate_string_file
+      validate_strings_file if @options[:validate]
+
       lang = nil
       lang = @options[:languages][0] if @options[:languages]
 
@@ -50,6 +52,8 @@ module Twine
     end
 
     def generate_all_string_files
+      validate_strings_file if @options[:validate]
+
       if !File.directory?(@options[:output_path])
         if @options[:create_folders]
           FileUtils.mkdir_p(@options[:output_path])
@@ -99,6 +103,8 @@ module Twine
     end
 
     def generate_loc_drop
+      validate_strings_file if @options[:validate]
+      
       require_rubyzip
 
       if File.file?(@options[:output_path])
@@ -179,10 +185,12 @@ module Twine
         errors << "Found duplicate string key(s):\n#{join_keys.call(duplicate_keys)}"
       end
 
-      if keys_without_tags.length == total_strings
-        errors << "None of your strings have tags."
-      elsif keys_without_tags.length > 0
-        errors << "Found strings without tags:\n#{join_keys.call(keys_without_tags)}"
+      if @options[:pedantic]
+        if keys_without_tags.length == total_strings
+          errors << "None of your strings have tags."
+        elsif keys_without_tags.length > 0
+          errors << "Found strings without tags:\n#{join_keys.call(keys_without_tags)}"
+        end
       end
 
       unless invalid_keys.empty?
diff --git a/test/test_cli.rb b/test/test_cli.rb
index cbce75f..9e95f3e 100644
--- a/test/test_cli.rb
+++ b/test/test_cli.rb
@@ -21,6 +21,11 @@ class CLITestCase < TwineTestCase
       assert_equal @strings_file_path, @options[:strings_file]
     end
 
+    def test_pedantic
+      parse "validate-strings-file #{@strings_file_path} --pedantic"
+      assert @options[:pedantic]
+    end
+
     def test_missing_parameter
       assert_raises Twine::Error do
         parse 'validate-strings-file'
@@ -49,6 +54,11 @@ class CLITestCase < TwineTestCase
       end
     end
 
+    def test_validate
+      parse "generate-string-file #{@strings_file_path} #{@output_path} --validate"
+      assert @options[:validate]
+    end
+
     def test_extra_parameter
       assert_raises Twine::Error do
         parse 'generate-string-file strings output extra'
@@ -77,6 +87,11 @@ class CLITestCase < TwineTestCase
       end
     end
 
+    def test_validate
+      parse "generate-all-string-files #{@strings_file_path} #{@output_dir} --validate"
+      assert @options[:validate]
+    end
+
     def test_extra_parameter
       assert_raises Twine::Error do
         parse "generate-all-string-files strings output extra"
@@ -149,6 +164,11 @@ class CLITestCase < TwineTestCase
       end
     end
 
+    def test_validate
+      parse "generate-loc-drop #{@strings_file_path} #{@output_path} --format apple --validate"
+      assert @options[:validate]
+    end
+
     def test_extra_parameter
       assert_raises Twine::Error do
         parse "generate-loc-drop strings output extra --format apple"
diff --git a/test/test_generate_all_string_files.rb b/test/test_generate_all_string_files.rb
index ac46219..4a9b8f3 100644
--- a/test/test_generate_all_string_files.rb
+++ b/test/test_generate_all_string_files.rb
@@ -8,13 +8,13 @@ class TestGenerateAllStringFiles < CommandTestCase
       options[:format] = 'apple'
       options[:create_folders] = create_folders
 
-      @twine_file = build_twine_file 'en', 'es' do
+      twine_file = build_twine_file 'en', 'es' do
         add_section 'Section' do
           add_row key: 'value'
         end
       end
 
-      Twine::Runner.new(options, @twine_file)
+      Twine::Runner.new(options, twine_file)
     end
 
     def test_fails_if_output_folder_does_not_exist
@@ -41,4 +41,36 @@ class TestGenerateAllStringFiles < CommandTestCase
       assert File.exists?(File.join(@output_dir, 'es.lproj')), "language folder 'es.lproj' should be created"
     end
   end
+
+  class TestDeliberate < CommandTestCase
+    def new_runner(validate)
+      Dir.mkdir File.join @output_dir, 'values-en'
+
+      options = {}
+      options[:output_path] = @output_dir
+      options[:format] = 'android'
+      options[:validate] = validate
+
+      twine_file = build_twine_file 'en' do
+        add_section 'Section' do
+          add_row key: 'value'
+          add_row key: 'value'
+        end
+      end
+
+      Twine::Runner.new(options, twine_file)
+    end
+
+    def test_does_not_validate_strings_file
+      prepare_mock_formatter Twine::Formatters::Android
+
+      new_runner(false).generate_all_string_files
+    end
+
+    def test_validates_strings_file_if_validate
+      assert_raises Twine::Error do
+        new_runner(true).generate_all_string_files
+      end
+    end
+  end
 end
diff --git a/test/test_generate_loc_drop.rb b/test/test_generate_loc_drop.rb
index e4c1d2b..4ef0979 100644
--- a/test/test_generate_loc_drop.rb
+++ b/test/test_generate_loc_drop.rb
@@ -41,4 +41,34 @@ class TestGenerateLocDrop < CommandTestCase
 
     @runner.generate_loc_drop
   end
+
+  class TestDeliberate < CommandTestCase
+    def new_runner(validate)
+      options = {}
+      options[:output_path] = @output_path
+      options[:format] = 'android'
+      options[:validate] = validate
+
+      twine_file = build_twine_file 'en' do
+        add_section 'Section' do
+          add_row key: 'value'
+          add_row key: 'value'
+        end
+      end
+
+      Twine::Runner.new(options, twine_file)
+    end
+
+    def test_does_not_validate_strings_file
+      prepare_mock_formatter Twine::Formatters::Android
+
+      new_runner(false).generate_loc_drop
+    end
+
+    def test_validates_strings_file_if_validate
+      assert_raises Twine::Error do
+        new_runner(true).generate_loc_drop
+      end
+    end
+  end
 end
diff --git a/test/test_generate_string_file.rb b/test/test_generate_string_file.rb
index ddaac5a..aa27eec 100644
--- a/test/test_generate_string_file.rb
+++ b/test/test_generate_string_file.rb
@@ -6,10 +6,10 @@ class TestGenerateStringFile < CommandTestCase
     options[:output_path] = File.join(@output_dir, file) if file
     options[:languages] = language if language
 
-    @strings = Twine::StringsFile.new
-    @strings.language_codes.concat KNOWN_LANGUAGES
+    strings = Twine::StringsFile.new
+    strings.language_codes.concat KNOWN_LANGUAGES
 
-    Twine::Runner.new(options, @strings)
+    Twine::Runner.new(options, strings)
   end
 
   def prepare_mock_write_file_formatter(formatter_class)
@@ -48,4 +48,35 @@ class TestGenerateStringFile < CommandTestCase
 
     new_runner(nil, "#{random_language}.xml").generate_string_file
   end
+
+  class TestDeliberate < CommandTestCase
+    def new_runner(validate)
+      options = {}
+      options[:output_path] = @output_path
+      options[:languages] = ['en']
+      options[:format] = 'android'
+      options[:validate] = validate
+
+      twine_file = build_twine_file 'en' do
+        add_section 'Section' do
+          add_row key: 'value'
+          add_row key: 'value'
+        end
+      end
+
+      Twine::Runner.new(options, twine_file)
+    end
+
+    def test_does_not_validate_strings_file
+      prepare_mock_formatter Twine::Formatters::Android
+
+      new_runner(false).generate_string_file
+    end
+
+    def test_validates_strings_file_if_validate
+      assert_raises Twine::Error do
+        new_runner(true).generate_string_file
+      end
+    end
+  end
 end
diff --git a/test/test_validate_strings_file.rb b/test/test_validate_strings_file.rb
index fcb6a27..c414e75 100644
--- a/test/test_validate_strings_file.rb
+++ b/test/test_validate_strings_file.rb
@@ -37,14 +37,6 @@ class TestValidateStringsFile < CommandTestCase
     end
   end
 
-  def test_reports_missing_tags
-    random_row.tags.clear
-
-    assert_raises Twine::Error do
-      Twine::Runner.new(@options, @twine_file).validate_strings_file
-    end
-  end
-
   def test_reports_invalid_characters_in_keys
     random_row.key[0] = "!?;:,^`´'\"\\|/(){}[]~-+*=#$%".chars.to_a.sample
 
@@ -52,4 +44,18 @@ class TestValidateStringsFile < CommandTestCase
       Twine::Runner.new(@options, @twine_file).validate_strings_file
     end
   end
+
+  def test_does_not_reports_missing_tags_by_default
+    random_row.tags.clear
+
+    Twine::Runner.new(@options, @twine_file).validate_strings_file
+  end
+
+  def test_reports_missing_tags
+    random_row.tags.clear
+
+    assert_raises Twine::Error do
+      Twine::Runner.new(@options.merge(pedantic: true), @twine_file).validate_strings_file
+    end
+  end
 end