diff --git a/CHANGELOG.md b/CHANGELOG.md
index e42041c..e1eda5b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Change Log
 
+## [0.5.1](https://github.com/dldevinc/paper-forms/tree/v0.5.1) - 2024-01-03
+
+-   Now you can set the `error_css_class` and `required_css_class` using Composer.
+
 ## [0.5.0](https://github.com/dldevinc/paper-forms/tree/v0.5.0) - 2024-01-02
 
 ### ⚠ BREAKING CHANGES
diff --git a/README.md b/README.md
index c8811fe..89b3a7b 100644
--- a/README.md
+++ b/README.md
@@ -133,6 +133,13 @@ class ExampleForm(forms.Form):
 Here, the `Composer` class provides labels and help text for the "name" and "age" fields, 
 offering clear instructions to users interacting with your forms.
 
+Additionally, developers can enhance the customization of the form's appearance 
+by utilizing the `error_css_class` and `required_css_class` attributes 
+within the `Composer` class. These attributes allow you to define specific CSS classes 
+for handling errors and indicating required fields, respectively. Notably, any values 
+set for these attributes in the `Composer` class take precedence over those specified 
+at the form level.
+
 ### Specifying Custom Template Names
 
 When using `paper-forms`, you have the flexibility to create custom templates for 
diff --git a/paper_forms/__init__.py b/paper_forms/__init__.py
index 3d18726..dd9b22c 100644
--- a/paper_forms/__init__.py
+++ b/paper_forms/__init__.py
@@ -1 +1 @@
-__version__ = "0.5.0"
+__version__ = "0.5.1"
diff --git a/paper_forms/boundfield.py b/paper_forms/boundfield.py
index 7ceaed3..47dd9d2 100644
--- a/paper_forms/boundfield.py
+++ b/paper_forms/boundfield.py
@@ -100,6 +100,30 @@ def get_context(
 
         return context
 
+    def css_classes(self, extra_classes=None):
+        if hasattr(extra_classes, "split"):
+            extra_classes = extra_classes.split()
+
+        # Remove duplicates while maintaining the order.
+        seen = set()
+        extra_classes = [
+            class_name
+            for class_name in (extra_classes or [])
+            if class_name not in seen and not seen.add(class_name)
+        ]
+
+        if self.errors:
+            if self.composer.error_css_class:
+                extra_classes.append(self.composer.error_css_class)
+            elif hasattr(self.form, "error_css_class"):
+                extra_classes.append(self.form.error_css_class)
+        if self.field.required:
+            if self.composer.required_css_class:
+                extra_classes.append(self.composer.required_css_class)
+            elif hasattr(self.form, "required_css_class"):
+                extra_classes.append(self.form.required_css_class)
+        return " ".join(extra_classes)
+
     @cached_property
     def widget(self) -> Widget:
         widget = self.composer.get_widget(self.name)
diff --git a/paper_forms/composer.py b/paper_forms/composer.py
index 1e19519..90bc0d3 100644
--- a/paper_forms/composer.py
+++ b/paper_forms/composer.py
@@ -1,5 +1,5 @@
 import copy
-from typing import Any, Optional
+from typing import Any, Optional, ClassVar
 
 from django.forms import BaseForm
 from django.forms.renderers import BaseRenderer
@@ -23,11 +23,13 @@ def __call__(cls, *args, **kwargs):
 
 class BaseComposer(metaclass=SingletonMeta):
     renderer = None
-    widgets: dict[str, Any] = None
-    labels: dict[str, str] = None
-    help_texts: dict[str, str] = None
-    css_classes: dict[str, str] = None
-    template_names: dict[str, str] = None
+    error_css_class: ClassVar[str] = None
+    required_css_class: ClassVar[str] = None
+    widgets: ClassVar[dict[str, Any]] = None
+    labels: ClassVar[dict[str, str]] = None
+    help_texts: ClassVar[dict[str, str]] = None
+    css_classes: ClassVar[dict[str, str]] = None
+    template_names: ClassVar[dict[str, str]] = None
 
     def get_renderer(self, form: BaseForm) -> BaseRenderer:
         renderer = self.renderer or form.default_renderer or conf.DEFAULT_FORM_RENDERER
diff --git a/tests/tests/test_boundfield.py b/tests/tests/test_boundfield.py
index 1dcb735..a7d8d0f 100644
--- a/tests/tests/test_boundfield.py
+++ b/tests/tests/test_boundfield.py
@@ -267,3 +267,41 @@ class MyForm(Form):
             "css_classes": "",
             "errors": [],
         }
+
+
+class TestCssClasses:
+    def test_get_values_from_composer(self):
+        class MyForm(Form):
+            error_css_class = "This will be overriden"
+            required_css_class = "This will be overriden"
+
+            name = CharField(
+                max_length=64,
+            )
+
+        class Composer(BaseComposer):
+            error_css_class = "invalid"
+            required_css_class = "required"
+
+        # Bound form
+        form = MyForm({})
+
+        bf = get_boundfield(form, "name", Composer())
+        css_classes = bf.css_classes()
+        assert css_classes == "invalid required"
+
+    def test_get_values_from_form(self):
+        class MyForm(Form):
+            error_css_class = "invalid"
+            required_css_class = "required"
+
+            name = CharField(
+                max_length=64,
+            )
+
+        # Bound form
+        form = MyForm({})
+
+        bf = get_boundfield(form, "name", BaseComposer())
+        css_classes = bf.css_classes()
+        assert css_classes == "invalid required"