diff --git a/doc/source/launchers.rst b/doc/source/launchers.rst
index 78d5839..8a8c932 100644
--- a/doc/source/launchers.rst
+++ b/doc/source/launchers.rst
@@ -273,9 +273,7 @@
   build:FUNCTION_NAME:NODE_NAME
 
 where **NODE_NAME** is the name or class of node on which the job
-should be run.  This can be specified by setting the ZUUL_NODE
-parameter in a parameter-function (see :ref:`includes` section in
-:ref:`zuulconf`).
+should be run.
 
 Zuul sends the ZUUL_* parameters described in `Zuul Parameters`_
 encoded in JSON format as the argument included with the
diff --git a/doc/source/zuul.rst b/doc/source/zuul.rst
index 102beac..ad6a061 100644
--- a/doc/source/zuul.rst
+++ b/doc/source/zuul.rst
@@ -261,26 +261,6 @@
 Zuul should perform.  There are three sections: pipelines, jobs, and
 projects.
 
-.. _includes:
-
-Includes
-""""""""
-
-Custom functions to be used in Zuul's configuration may be provided
-using the ``includes`` directive.  It accepts a list of files to
-include, and currently supports one type of inclusion, a python file::
-
-  includes:
-    - python-file: local_functions.py
-
-**python-file**
-  The path to a python file (either an absolute path or relative to the
-  directory name of :ref:`layout_config <layout_config>`).  The
-  file will be loaded and objects that it defines will be placed in a
-  special environment which can be referenced in the Zuul configuration.
-  Currently only the parameter-function attribute of a Job uses this
-  feature.
-
 Pipelines
 """""""""
 
@@ -800,33 +780,6 @@
 
 **tags (optional)**
   A list of arbitrary strings which will be associated with the job.
-  Can be used by the parameter-function to alter behavior based on
-  their presence on a job.  If the job name is a regular expression,
-  tags will accumulate on jobs that match.
-
-**parameter-function (optional)**
-  Specifies a function that should be applied to the parameters before
-  the job is launched.  The function should be defined in a python file
-  included with the :ref:`includes` directive.  The function
-  should have the following signature:
-
-  .. function:: parameters(item, job, parameters)
-
-     Manipulate the parameters passed to a job before a build is
-     launched.  The ``parameters`` dictionary will already contain the
-     standard Zuul job parameters, and is expected to be modified
-     in-place.
-
-     :param item: the current queue item
-     :type item: zuul.model.QueueItem
-     :param job: the job about to be run
-     :type job: zuul.model.Job
-     :param parameters: parameters to be passed to the job
-     :type parameters: dict
-
-  If the parameter **ZUUL_NODE** is set by this function, then it will
-  be used to specify on what node (or class of node) the job should be
-  run.
 
 **swift**
   If :ref:`swift` is configured then each job can define a destination
diff --git a/zuul/launcher/client.py b/zuul/launcher/client.py
index 96a524d..a9b8b11 100644
--- a/zuul/launcher/client.py
+++ b/zuul/launcher/client.py
@@ -13,7 +13,6 @@
 # under the License.
 
 import gear
-import inspect
 import json
 import logging
 import os
@@ -284,16 +283,6 @@
                 for key, value in swift_instructions.items():
                     params['_'.join(['SWIFT', name, key])] = value
 
-        if callable(job.parameter_function):
-            pargs = inspect.getargspec(job.parameter_function)
-            if len(pargs.args) == 2:
-                job.parameter_function(item, params)
-            else:
-                job.parameter_function(item, job, params)
-            self.log.debug("Custom parameter function used for job %s, "
-                           "change: %s, params: %s" % (job, item.change,
-                                                       params))
-
     def launch(self, job, item, pipeline, dependent_items=[]):
         uuid = str(uuid4().hex)
         self.log.info(
diff --git a/zuul/layoutvalidator.py b/zuul/layoutvalidator.py
index 1f008c3..57c1fad 100644
--- a/zuul/layoutvalidator.py
+++ b/zuul/layoutvalidator.py
@@ -50,9 +50,6 @@
 
 
 class LayoutSchema(object):
-    include = {'python-file': str}
-    includes = [include]
-
     manager = v.Any('IndependentPipelineManager',
                     'DependentPipelineManager')
 
@@ -129,7 +126,6 @@
            'voting': bool,
            'mutex': str,
            'tags': toList(str),
-           'parameter-function': str,
            'branch': toList(str),
            'files': toList(str),
            'swift': toList(swift),
diff --git a/zuul/model.py b/zuul/model.py
index 9cd9d09..a691f96 100644
--- a/zuul/model.py
+++ b/zuul/model.py
@@ -424,7 +424,6 @@
         branch_matcher=None,
         file_matcher=None,
         irrelevant_file_matcher=None,  # skip-if
-        parameter_function=None,  # TODOv3(jeblair): remove
         tags=set(),
         mutex=None,
     )