diff --git a/mistral/api/controllers/v2/validation.py b/mistral/api/controllers/v2/validation.py
index 5c91fda75..e43691315 100644
--- a/mistral/api/controllers/v2/validation.py
+++ b/mistral/api/controllers/v2/validation.py
@@ -32,7 +32,7 @@ class SpecValidationController(rest.RestController):
         definition = pecan.request.text
 
         try:
-            self._parse_func(definition)
+            self._parse_func(definition, validate=True)
         except exc.DSLParsingException as e:
             return {'valid': False, 'error': str(e)}
 
diff --git a/mistral/lang/base.py b/mistral/lang/base.py
index 4fdb03ab4..57fed494a 100644
--- a/mistral/lang/base.py
+++ b/mistral/lang/base.py
@@ -52,7 +52,7 @@ ALL = (
 PARAMS_PTRN = re.compile("([-_\w]+)=(%s)" % "|".join(ALL))
 
 
-def instantiate_spec(spec_cls, data):
+def instantiate_spec(spec_cls, data, validate=False):
     """Instantiates specification accounting for specification hierarchies.
 
     :param spec_cls: Specification concrete or base class. In case if base
@@ -60,17 +60,22 @@ def instantiate_spec(spec_cls, data):
         _polymorphic_key and _polymorphic_value in order to find a concrete
         class that needs to be instantiated.
     :param data: Raw specification data as a dictionary.
+    :type data: dict
+    :param validate: If it equals False then semantics and schema validation
+        will be skipped
+    :type validate: bool
     """
 
     if issubclass(spec_cls, BaseSpecList):
         # Ignore polymorphic search for specification lists because
         # it doesn't make sense for them.
-        return spec_cls(data)
+        return spec_cls(data, validate)
 
     if not hasattr(spec_cls, '_polymorphic_key'):
-        spec = spec_cls(data)
+        spec = spec_cls(data, validate)
 
-        spec.validate_semantics()
+        if validate:
+            spec.validate_semantics()
 
         return spec
 
@@ -101,9 +106,10 @@ def instantiate_spec(spec_cls, data):
             )
 
         if cls._polymorphic_value == data.get(key_name, key_default):
-            spec = cls(data)
+            spec = cls(data, validate)
 
-            spec.validate_semantics()
+            if validate:
+                spec.validate_semantics()
 
             return spec
 
@@ -176,10 +182,12 @@ class BaseSpec(object):
 
         return schema
 
-    def __init__(self, data):
+    def __init__(self, data, validate):
         self._data = data
+        self._validate = validate
 
-        self.validate_schema()
+        if validate:
+            self.validate_schema()
 
     def validate_schema(self):
         """Validates DSL entity schema that this specification represents.
@@ -227,10 +235,10 @@ class BaseSpec(object):
     def _spec_property(self, prop_name, spec_cls):
         prop_val = self._data.get(prop_name)
 
-        return (
-            instantiate_spec(spec_cls, prop_val) if prop_val is not None
-            else None
-        )
+        if prop_val is not None:
+            return instantiate_spec(spec_cls, prop_val, self._validate)
+        else:
+            return None
 
     def _group_spec(self, spec_cls, *prop_names):
         if not prop_names:
@@ -244,7 +252,7 @@ class BaseSpec(object):
             if prop_val:
                 data[prop_name] = prop_val
 
-        return instantiate_spec(spec_cls, data)
+        return instantiate_spec(spec_cls, data, self._validate)
 
     def _inject_version(self, prop_names):
         for prop_name in prop_names:
@@ -322,8 +330,8 @@ class BaseListSpec(BaseSpec):
         "required": ["version"],
     }
 
-    def __init__(self, data):
-        super(BaseListSpec, self).__init__(data)
+    def __init__(self, data, validate):
+        super(BaseListSpec, self).__init__(data, validate)
 
         self.items = []
 
@@ -331,7 +339,10 @@ class BaseListSpec(BaseSpec):
             if k != 'version':
                 v['name'] = k
                 self._inject_version([k])
-                self.items.append(instantiate_spec(self.item_class, v))
+
+                self.items.append(
+                    instantiate_spec(self.item_class, v, validate)
+                )
 
     def validate_schema(self):
         super(BaseListSpec, self).validate_schema()
@@ -357,7 +368,7 @@ class BaseSpecList(object):
 
     _version = '2.0'
 
-    def __init__(self, data):
+    def __init__(self, data, validate):
         self.items = {}
 
         for k, v in data.items():
@@ -369,7 +380,7 @@ class BaseSpecList(object):
                     v['name'] = k
                     v['version'] = self._version
 
-                self.items[k] = instantiate_spec(self.item_class, v)
+                self.items[k] = instantiate_spec(self.item_class, v, validate)
 
     def item_keys(self):
         return self.items.keys()
diff --git a/mistral/lang/parser.py b/mistral/lang/parser.py
index dc92c184a..0af0bf9b9 100644
--- a/mistral/lang/parser.py
+++ b/mistral/lang/parser.py
@@ -80,15 +80,17 @@ def _get_spec_version(spec_dict):
 # Factory methods to get specifications either from raw YAML formatted text or
 # from dictionaries parsed from YAML formatted text.
 
-def get_workbook_spec(spec_dict):
+def get_workbook_spec(spec_dict, validate):
     if _get_spec_version(spec_dict) == V2_0:
-        return base.instantiate_spec(wb_v2.WorkbookSpec, spec_dict)
+        return base.instantiate_spec(
+            wb_v2.WorkbookSpec, spec_dict, validate
+        )
 
     return None
 
 
-def get_workbook_spec_from_yaml(text):
-    return get_workbook_spec(parse_yaml(text))
+def get_workbook_spec_from_yaml(text, validate=True):
+    return get_workbook_spec(parse_yaml(text), validate)
 
 
 def get_action_spec(spec_dict):
@@ -106,12 +108,14 @@ def get_action_spec_from_yaml(text, action_name):
     return get_action_spec(spec_dict)
 
 
-def get_action_list_spec(spec_dict):
-    return base.instantiate_spec(actions_v2.ActionListSpec, spec_dict)
+def get_action_list_spec(spec_dict, validate):
+    return base.instantiate_spec(
+        actions_v2.ActionListSpec, spec_dict, validate
+    )
 
 
-def get_action_list_spec_from_yaml(text):
-    return get_action_list_spec(parse_yaml(text))
+def get_action_list_spec_from_yaml(text, validate=True):
+    return get_action_list_spec(parse_yaml(text), validate=validate)
 
 
 def get_workflow_spec(spec_dict):
@@ -130,16 +134,18 @@ def get_workflow_spec(spec_dict):
     return None
 
 
-def get_workflow_list_spec(spec_dict):
-    return base.instantiate_spec(wf_v2.WorkflowListSpec, spec_dict)
+def get_workflow_list_spec(spec_dict, validate):
+    return base.instantiate_spec(
+        wf_v2.WorkflowListSpec, spec_dict, validate
+    )
 
 
 def get_workflow_spec_from_yaml(text):
     return get_workflow_spec(parse_yaml(text))
 
 
-def get_workflow_list_spec_from_yaml(text):
-    return get_workflow_list_spec(parse_yaml(text))
+def get_workflow_list_spec_from_yaml(text, validate=True):
+    return get_workflow_list_spec(parse_yaml(text), validate)
 
 
 def get_task_spec(spec_dict):
diff --git a/mistral/lang/v2/actions.py b/mistral/lang/v2/actions.py
index 2d37d9d6a..a736967a5 100644
--- a/mistral/lang/v2/actions.py
+++ b/mistral/lang/v2/actions.py
@@ -34,8 +34,8 @@ class ActionSpec(base.BaseSpec):
         "additionalProperties": False
     }
 
-    def __init__(self, data):
-        super(ActionSpec, self).__init__(data)
+    def __init__(self, data, validate):
+        super(ActionSpec, self).__init__(data, validate)
 
         self._name = data['name']
         self._description = data.get('description')
diff --git a/mistral/lang/v2/on_clause.py b/mistral/lang/v2/on_clause.py
index cb65312af..e5c1bb7e5 100644
--- a/mistral/lang/v2/on_clause.py
+++ b/mistral/lang/v2/on_clause.py
@@ -94,8 +94,8 @@ class OnClauseSpec(base.BaseSpec):
         ]
     }
 
-    def __init__(self, data):
-        super(OnClauseSpec, self).__init__(data)
+    def __init__(self, data, validate):
+        super(OnClauseSpec, self).__init__(data, validate)
 
         if not isinstance(data, dict):
             # Old simple schema.
diff --git a/mistral/lang/v2/policies.py b/mistral/lang/v2/policies.py
index 775b07e98..b18e0d195 100644
--- a/mistral/lang/v2/policies.py
+++ b/mistral/lang/v2/policies.py
@@ -37,8 +37,8 @@ class PoliciesSpec(base.BaseSpec):
     def get_schema(cls, includes=['definitions']):
         return super(PoliciesSpec, cls).get_schema(includes)
 
-    def __init__(self, data):
-        super(PoliciesSpec, self).__init__(data)
+    def __init__(self, data, validate):
+        super(PoliciesSpec, self).__init__(data, validate)
 
         self._retry = self._spec_property('retry', retry_policy.RetrySpec)
         self._wait_before = data.get('wait-before', 0)
diff --git a/mistral/lang/v2/publish.py b/mistral/lang/v2/publish.py
index a3adc1031..9515aa338 100644
--- a/mistral/lang/v2/publish.py
+++ b/mistral/lang/v2/publish.py
@@ -29,8 +29,8 @@ class PublishSpec(base.BaseSpec):
         "additionalProperties": False
     }
 
-    def __init__(self, data):
-        super(PublishSpec, self).__init__(data)
+    def __init__(self, data, validate):
+        super(PublishSpec, self).__init__(data, validate)
 
         self._branch = self._data.get('branch')
         self._global = self._data.get('global')
diff --git a/mistral/lang/v2/retry_policy.py b/mistral/lang/v2/retry_policy.py
index 224d1886d..cc69149f3 100644
--- a/mistral/lang/v2/retry_policy.py
+++ b/mistral/lang/v2/retry_policy.py
@@ -54,10 +54,10 @@ class RetrySpec(base.BaseSpec):
     def get_schema(cls, includes=['definitions']):
         return super(RetrySpec, cls).get_schema(includes)
 
-    def __init__(self, data):
+    def __init__(self, data, validate):
         data = self._transform_retry_one_line(data)
 
-        super(RetrySpec, self).__init__(data)
+        super(RetrySpec, self).__init__(data, validate)
 
         self._break_on = data.get('break-on')
         self._count = data.get('count')
diff --git a/mistral/lang/v2/task_defaults.py b/mistral/lang/v2/task_defaults.py
index acb1b4803..08f8bee72 100644
--- a/mistral/lang/v2/task_defaults.py
+++ b/mistral/lang/v2/task_defaults.py
@@ -53,8 +53,8 @@ class TaskDefaultsSpec(base.BaseSpec):
     def get_schema(cls, includes=['definitions']):
         return super(TaskDefaultsSpec, cls).get_schema(includes)
 
-    def __init__(self, data):
-        super(TaskDefaultsSpec, self).__init__(data)
+    def __init__(self, data, validate):
+        super(TaskDefaultsSpec, self).__init__(data, validate)
 
         self._policies = self._group_spec(
             policies.PoliciesSpec,
diff --git a/mistral/lang/v2/tasks.py b/mistral/lang/v2/tasks.py
index 96ee80403..70ad9f1b2 100644
--- a/mistral/lang/v2/tasks.py
+++ b/mistral/lang/v2/tasks.py
@@ -107,8 +107,8 @@ class TaskSpec(base.BaseSpec):
         ]
     }
 
-    def __init__(self, data):
-        super(TaskSpec, self).__init__(data)
+    def __init__(self, data, validate):
+        super(TaskSpec, self).__init__(data, validate)
 
         self._name = data['name']
         self._description = data.get('description')
@@ -248,10 +248,14 @@ class TaskSpec(base.BaseSpec):
         spec = None
 
         if state == states.SUCCESS and self._publish:
-            spec = publish.PublishSpec({'branch': self._publish})
+            spec = publish.PublishSpec(
+                {'branch': self._publish},
+                validate=self._validate
+            )
         elif state == states.ERROR and self._publish_on_error:
             spec = publish.PublishSpec(
-                {'branch': self._publish_on_error}
+                {'branch': self._publish_on_error},
+                validate=self._validate
             )
 
         return spec
@@ -291,8 +295,8 @@ class DirectWorkflowTaskSpec(TaskSpec):
         _direct_workflow_schema
     )
 
-    def __init__(self, data):
-        super(DirectWorkflowTaskSpec, self).__init__(data)
+    def __init__(self, data, validate):
+        super(DirectWorkflowTaskSpec, self).__init__(data, validate)
 
         self._join = data.get('join')
 
@@ -376,8 +380,8 @@ class ReverseWorkflowTaskSpec(TaskSpec):
         _reverse_workflow_schema
     )
 
-    def __init__(self, data):
-        super(ReverseWorkflowTaskSpec, self).__init__(data)
+    def __init__(self, data, validate):
+        super(ReverseWorkflowTaskSpec, self).__init__(data, validate)
 
         self._requires = data.get('requires', [])
 
diff --git a/mistral/lang/v2/workbook.py b/mistral/lang/v2/workbook.py
index 72c93d5f9..22a501ab1 100644
--- a/mistral/lang/v2/workbook.py
+++ b/mistral/lang/v2/workbook.py
@@ -51,8 +51,8 @@ class WorkbookSpec(base.BaseSpec):
         "additionalProperties": False
     }
 
-    def __init__(self, data):
-        super(WorkbookSpec, self).__init__(data)
+    def __init__(self, data, validate):
+        super(WorkbookSpec, self).__init__(data, validate)
 
         self._inject_version(['actions', 'workflows'])
 
diff --git a/mistral/lang/v2/workflows.py b/mistral/lang/v2/workflows.py
index 2d60627c4..af1f1cadc 100644
--- a/mistral/lang/v2/workflows.py
+++ b/mistral/lang/v2/workflows.py
@@ -44,8 +44,8 @@ class WorkflowSpec(base.BaseSpec):
         "additionalProperties": False
     }
 
-    def __init__(self, data):
-        super(WorkflowSpec, self).__init__(data)
+    def __init__(self, data, validate):
+        super(WorkflowSpec, self).__init__(data, validate)
 
         self._name = data['name']
         self._description = data.get('description')
@@ -152,8 +152,8 @@ class DirectWorkflowSpec(WorkflowSpec):
         }
     }
 
-    def __init__(self, data):
-        super(DirectWorkflowSpec, self).__init__(data)
+    def __init__(self, data, validate):
+        super(DirectWorkflowSpec, self).__init__(data, validate)
 
         # Init simple dictionary based caches for inbound and
         # outbound task specifications. In fact, we don't need
diff --git a/mistral/services/workbooks.py b/mistral/services/workbooks.py
index f55333cda..77fafebc6 100644
--- a/mistral/services/workbooks.py
+++ b/mistral/services/workbooks.py
@@ -18,7 +18,9 @@ from mistral.services import actions
 
 
 def create_workbook_v2(definition, namespace='', scope='private'):
-    wb_spec = spec_parser.get_workbook_spec_from_yaml(definition)
+    wb_spec = spec_parser.get_workbook_spec_from_yaml(
+        definition, validate=True
+    )
 
     wb_values = _get_workbook_values(
         wb_spec,
@@ -36,7 +38,9 @@ def create_workbook_v2(definition, namespace='', scope='private'):
 
 
 def update_workbook_v2(definition, namespace='', scope='private'):
-    wb_spec = spec_parser.get_workbook_spec_from_yaml(definition)
+    wb_spec = spec_parser.get_workbook_spec_from_yaml(
+        definition, validate=True
+    )
 
     values = _get_workbook_values(wb_spec, definition, scope, namespace)
 
diff --git a/mistral/services/workflows.py b/mistral/services/workflows.py
index c9e9a1d8f..7a49ccb00 100644
--- a/mistral/services/workflows.py
+++ b/mistral/services/workflows.py
@@ -54,7 +54,9 @@ def sync_db():
 def create_workflows(definition, scope='private', is_system=False,
                      run_in_tx=True, namespace=''):
     LOG.debug("Creating workflows")
-    wf_list_spec = spec_parser.get_workflow_list_spec_from_yaml(definition)
+    wf_list_spec = spec_parser.get_workflow_list_spec_from_yaml(
+        definition, validate=True
+    )
     db_wfs = []
 
     if run_in_tx:
@@ -98,7 +100,9 @@ def update_workflows(definition, scope='private', identifier=None,
                      namespace=''):
     LOG.debug("Updating workflows")
 
-    wf_list_spec = spec_parser.get_workflow_list_spec_from_yaml(definition)
+    wf_list_spec = spec_parser.get_workflow_list_spec_from_yaml(
+        definition, validate=True
+    )
     wfs = wf_list_spec.get_workflows()
 
     if identifier and len(wfs) > 1: