diff --git a/CHANGES.rst b/CHANGES.rst
index 87c74e0..8234597 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -4,6 +4,9 @@ Changelog
 1.0 (unreleased)
 ----------------
 
+- Birthday is now optional as a behaviour.
+  [thomasdesvenain]
+
 - Use (-200, 1) years range for birthday field.
   [vincentfretin]
 
diff --git a/src/collective/contact/core/adapters.py b/src/collective/contact/core/adapters.py
index 6588e9c..791a74d 100644
--- a/src/collective/contact/core/adapters.py
+++ b/src/collective/contact/core/adapters.py
@@ -6,6 +6,7 @@ from Products.CMFPlone.utils import safe_unicode
 from collective.contact.core.interfaces import IVCard, IContactable
 from collective.contact.core.content.held_position import IHeldPosition,\
                                                              HeldPosition
+from collective.contact.core.behaviors import IBirthday
 
 
 class HeldPositionVCard(grok.Adapter):
@@ -35,7 +36,7 @@ class HeldPositionVCard(grok.Adapter):
         vcard.add('fn')
         vcard.fn.value = ' '.join([e for e in (firstname, lastname) if e])
 
-        if person.birthday is not None:
+        if IBirthday.providedBy(person) and person.birthday is not None:
             vcard.add('bday')
             vcard.bday.value = person.birthday.isoformat()
 
diff --git a/src/collective/contact/core/behaviors.py b/src/collective/contact/core/behaviors.py
index 859b549..36d8b47 100644
--- a/src/collective/contact/core/behaviors.py
+++ b/src/collective/contact/core/behaviors.py
@@ -3,14 +3,17 @@ from zope.interface import Interface
 from zope import schema
 from Acquisition import aq_base
 
+from z3c.form.widget import ComputedWidgetAttribute
+from z3c.form.widget import FieldWidget
 from plone.supermodel import model
+
 from plone.supermodel.directives import fieldset
 from plone.autoform.interfaces import IFormFieldProvider
 from plone.autoform import directives as form
 from plone.formwidget.masterselect import MasterSelectBoolField
+from plone.formwidget.datetime.z3cform import DateWidget
 from plone.app.textfield import RichText
 from plone.app.dexterity.browser.types import TypeSchemaContext
-from z3c.form.widget import ComputedWidgetAttribute
 
 from Products.CMFDefault.utils import checkEmailAddress
 from Products.CMFDefault.exceptions import EmailAddressInvalid
@@ -233,6 +236,22 @@ DefaultParentAddress = ComputedWidgetAttribute(
     field=IContactDetails['parent_address'], view=Interface)
 
 
+
+def DateFieldWidget(field, request):
+    """IFieldWidget factory for DatetimeWidget."""
+    widget = FieldWidget(field, DateWidget(request))
+    widget.years_range = (-200, 1)
+    return widget
+
+
+class IBirthday(model.Schema):
+
+    form.widget(birthday=DateFieldWidget)
+    birthday = schema.Date(
+        title=_("Birthday"),
+        required=False,
+        )
+
 class IRelatedOrganizations(model.Schema):
     """A content on which we can attach organizations
     """
diff --git a/src/collective/contact/core/behaviors.zcml b/src/collective/contact/core/behaviors.zcml
index 41324ae..a7da041 100644
--- a/src/collective/contact/core/behaviors.zcml
+++ b/src/collective/contact/core/behaviors.zcml
@@ -21,6 +21,12 @@
         provides=".behaviors.IGlobalPositioning"
         />
 
+    <plone:behavior
+        title="Birthday"
+        description="Contact have a birthday."
+        provides=".behaviors.IBirthday"
+        />
+        
     <plone:behavior
         title="Related organizations"
         description="We can attach organizations on content."
diff --git a/src/collective/contact/core/browser/contact.py b/src/collective/contact/core/browser/contact.py
index 4410036..a8b68f2 100644
--- a/src/collective/contact/core/browser/contact.py
+++ b/src/collective/contact/core/browser/contact.py
@@ -4,6 +4,7 @@ from collective.contact.core.browser.contactable import BaseView
 from collective.contact.core.browser.utils import get_ttw_fields,\
     date_to_DateTime
 from collective.contact.core.interfaces import IContactable
+from collective.contact.core.behaviors import IBirthday
 
 
 class Contact(BaseView):
@@ -35,11 +36,14 @@ class Contact(BaseView):
         self.person = person
         self.fullname = person.Title()
         self.title = held_position.Title()
-
-        birthday = person.birthday
-        if birthday is not None:
-            birthday = date_to_DateTime(birthday)
-            self.birthday = self.context.toLocalizedTime(birthday)
+        
+        if IBirthday.providedBy(person):
+            birthday = person.birthday
+            if birthday is not None:
+                birthday = date_to_DateTime(birthday)
+                self.birthday = self.context.toLocalizedTime(birthday)
+        else:
+            self.birthday = None
 
         self.gender = person.gender or ''
 
diff --git a/src/collective/contact/core/browser/person.py b/src/collective/contact/core/browser/person.py
index 320e8ea..31dc7d0 100644
--- a/src/collective/contact/core/browser/person.py
+++ b/src/collective/contact/core/browser/person.py
@@ -4,6 +4,7 @@ from collective.contact.core.browser.contactable import BaseView
 from collective.contact.core.browser.utils import date_to_DateTime,\
                                                      get_ttw_fields
 from collective.contact.core.interfaces import IContactable
+from collective.contact.core.behaviors import IBirthday
 
 
 class Person(BaseView):
@@ -21,10 +22,13 @@ class Person(BaseView):
         person = self.person
 
         self.name = person.Title()
-        birthday = person.birthday
-        if birthday is not None:
-            birthday = date_to_DateTime(birthday)
-            self.birthday = self.context.toLocalizedTime(birthday)
+        if IBirthday.providedBy(person):
+            birthday = person.birthday
+            if birthday is not None:
+                birthday = date_to_DateTime(birthday)
+                self.birthday = self.context.toLocalizedTime(birthday)
+        else:
+            self.birthday = ""
 
         self.person_title = person.person_title
         self.gender = person.gender or ''
diff --git a/src/collective/contact/core/content/person.py b/src/collective/contact/core/content/person.py
index cc6ac2d..704dde6 100644
--- a/src/collective/contact/core/content/person.py
+++ b/src/collective/contact/core/content/person.py
@@ -3,7 +3,6 @@ from zope.interface import implements
 from zope.interface import Attribute
 from z3c.form.interfaces import NO_VALUE
 from z3c.form.browser.radio import RadioFieldWidget
-from z3c.form.widget import FieldWidget
 
 from five import grok
 
@@ -12,7 +11,6 @@ from plone.dexterity.content import Container
 from plone.dexterity.schema import DexteritySchemaPolicy
 from plone.namedfile.field import NamedImage
 from plone.supermodel import model
-from plone.formwidget.datetime.z3cform import DateWidget
 
 from collective.contact.core import _
 from collective.contact.core.browser.contactable import Contactable
@@ -20,13 +18,6 @@ from collective.contact.widget.interfaces import IContactContent
 from collective.contact.core.content.held_position import IHeldPosition
 
 
-def DateFieldWidget(field, request):
-    """IFieldWidget factory for DatetimeWidget."""
-    widget = FieldWidget(field, DateWidget(request))
-    widget.years_range = (-200, 1)
-    return widget
-
-
 class IPerson(model.Schema, IContactContent):
     """Interface for Person content type"""
 
@@ -50,11 +41,6 @@ class IPerson(model.Schema, IContactContent):
         title=_("Person title"),
         required=False,
         )
-    form.widget(birthday=DateFieldWidget)
-    birthday = schema.Date(
-        title=_("Birthday"),
-        required=False,
-        )
     photo = NamedImage(
         title=_("Photo"),
         required=False,
@@ -64,6 +50,7 @@ class IPerson(model.Schema, IContactContent):
         """Returns held positions of this person
         """
 
+
 class PersonContactableAdapter(Contactable):
     """Contactable adapter for Person content type"""
 
@@ -97,7 +84,10 @@ class Person(Container):
 
     def get_held_positions(self):
         return [obj for obj in self.values() if IHeldPosition.providedBy(obj)]
-
+    
+    def get_held_positions_titles(self):
+        return [p.Title() for p in self.get_held_positions()]
+    
 
 class PersonSchemaPolicy(grok.GlobalUtility,
                          DexteritySchemaPolicy):
diff --git a/src/collective/contact/core/profiles/default/types/person.xml b/src/collective/contact/core/profiles/default/types/person.xml
index 47b588c..df154ad 100644
--- a/src/collective/contact/core/profiles/default/types/person.xml
+++ b/src/collective/contact/core/profiles/default/types/person.xml
@@ -23,6 +23,7 @@
  <property name="behaviors">
   <element value="plone.app.content.interfaces.INameFromTitle"/>
   <element value="collective.contact.core.behaviors.IContactDetails" />
+  <element value="collective.contact.core.behaviors.IBirthday" />
 </property>
  <property name="schema" />
  <!-- DO NOT use a model_source or it removes manually added fields while reapplying the profile -->
diff --git a/src/collective/contact/core/profiles/testing/types/testtype.xml b/src/collective/contact/core/profiles/testing/types/testtype.xml
index cef2be5..78269d3 100644
--- a/src/collective/contact/core/profiles/testing/types/testtype.xml
+++ b/src/collective/contact/core/profiles/testing/types/testtype.xml
@@ -21,6 +21,7 @@
  <property name="behaviors">
  	<element value="collective.contact.core.behaviors.IContactDetails" />
  	<element value="collective.contact.core.behaviors.IGlobalPositioning" />
+ 	<element value="collective.contact.core.behaviors.IBirthday" />
 </property>
  <property name="schema" />
  <!-- DO NOT use a model_source or it removes manually added fields while reapplying the profile -->
diff --git a/src/collective/contact/core/tests/test_behaviors.py b/src/collective/contact/core/tests/test_behaviors.py
index 37ce58d..a0494fa 100644
--- a/src/collective/contact/core/tests/test_behaviors.py
+++ b/src/collective/contact/core/tests/test_behaviors.py
@@ -12,7 +12,7 @@ from ecreall.helpers.testing.base import BaseTest
 
 from collective.contact.core.testing import INTEGRATION
 from collective.contact.core.behaviors import IContactDetails,\
-    IGlobalPositioning
+    IGlobalPositioning, IBirthday
 
 
 class TestBehaviors(unittest.TestCase, BaseTest):
@@ -33,18 +33,22 @@ class TestBehaviors(unittest.TestCase, BaseTest):
                 name='collective.contact.core.behaviors.IContactDetails')
         global_positioning_behavior = getUtility(IBehavior,
                 name='collective.contact.core.behaviors.IGlobalPositioning')
+        birthday_behavior = getUtility(IBehavior,
+                name='collective.contact.core.behaviors.IBirthday')
         self.assertEqual(contact_details_behavior.interface, IContactDetails)
         self.assertEqual(global_positioning_behavior.interface,
                          IGlobalPositioning)
+        self.assertEqual(birthday_behavior.interface, IBirthday)
         IFormFieldProvider.providedBy(contact_details_behavior.interface)
         IFormFieldProvider.providedBy(global_positioning_behavior.interface)
+        IFormFieldProvider.providedBy(birthday_behavior.interface)
 
     def test_contact_details_fields(self):
         item = self.testitem
         self.assertIsNone(item.getAttributes())
         for attr in ('country', 'region', 'zip_code', 'city', 'street',
                      'number', 'im_handle', 'cell_phone', 'phone', 'email',
-                     'additional_address_details'):
+                     'additional_address_details', 'birthday'):
             self.assertTrue(hasattr(item, attr))
         item.phone = '0655443322'
         item.email = 'toto@example.com'