diff --git a/modules/project/CHANGELOG b/modules/project/CHANGELOG
index 5998d60b65..e4743c75d8 100644
--- a/modules/project/CHANGELOG
+++ b/modules/project/CHANGELOG
@@ -1,3 +1,4 @@
+* Add number to the work efforts
 * Add support for Python 3.14
 * Remove support for Python 3.9
 
diff --git a/modules/project/doc/design.rst b/modules/project/doc/design.rst
index 82a220b211..6fad13a881 100644
--- a/modules/project/doc/design.rst
+++ b/modules/project/doc/design.rst
@@ -13,8 +13,8 @@ Work Effort
 The *Work Effort* concept is used to represent work that must be done for
 projects, or parts of projects.
 
-Each *Work Effort* is described by a name and a type, and there is space
-for additional comments to be added when required.
+Each *Work Effort* is described by a name, a number and a type, and there is
+space for additional comments to be added when required.
 
 The estimated time and effort needed for the work is recorded, and it is also
 possible to track the actual time and effort required.
diff --git a/modules/project/message.xml b/modules/project/message.xml
index da2f0a59c3..d9dbb2ad2b 100644
--- a/modules/project/message.xml
+++ b/modules/project/message.xml
@@ -3,6 +3,9 @@
 this repository contains the full copyright notices and license terms. -->
 <tryton>
     <data grouped="1">
+        <record model="ir.message" id="msg_work_number_unique">
+            <field name="text">The number on work must be unique.</field>
+        </record>
         <record model="ir.message" id="msg_work_invalid_progress_status">
             <field name="text">To set work "%(work)s" in "%(status)s" status, you must increase its progress up to at least %(progress)s.</field>
         </record>
diff --git a/modules/project/tests/scenario_project.rst b/modules/project/tests/scenario_project.rst
new file mode 100644
index 0000000000..f0ca6a0250
--- /dev/null
+++ b/modules/project/tests/scenario_project.rst
@@ -0,0 +1,29 @@
+================
+Project Scenario
+================
+
+Imports::
+
+    >>> from proteus import Model
+    >>> from trytond.modules.company.tests.tools import create_company
+    >>> from trytond.tests.tools import activate_modules
+
+Activate project::
+
+    >>> config = activate_modules('project', create_company)
+
+    >>> Work = Model.get('project.work')
+
+Create a project with a task::
+
+    >>> project = Work(type='project', name="Project")
+    >>> task = project.children.new(type='task', name="Task")
+    >>> project.save()
+    >>> task, = project.children
+
+Check works have numbers::
+
+    >>> bool(project.number)
+    True
+    >>> bool(task.number)
+    True
diff --git a/modules/project/tryton.cfg b/modules/project/tryton.cfg
index d3e91c3074..f959b31bd3 100644
--- a/modules/project/tryton.cfg
+++ b/modules/project/tryton.cfg
@@ -14,6 +14,8 @@ xml:
 
 [register]
 model:
+    work.Configuration
+    work.ConfigurationSequence
     # Before Work because status default value is read from WorkStatus
     work.WorkStatus
     work.Work
diff --git a/modules/project/view/project_configuration_form.xml b/modules/project/view/project_configuration_form.xml
new file mode 100644
index 0000000000..8b20ea5b2c
--- /dev/null
+++ b/modules/project/view/project_configuration_form.xml
@@ -0,0 +1,7 @@
+<?xml version="1.0"?>
+<!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
+this repository contains the full copyright notices and license terms. -->
+<form>
+    <label name="work_sequence"/>
+    <field name="work_sequence"/>
+</form>
diff --git a/modules/project/view/work_form.xml b/modules/project/view/work_form.xml
index 9ab705c1ba..79881fc924 100644
--- a/modules/project/view/work_form.xml
+++ b/modules/project/view/work_form.xml
@@ -3,9 +3,12 @@
 this repository contains the full copyright notices and license terms. -->
 <form col="6">
     <label name="name"/>
-    <field name="name" colspan="3"/>
+    <field name="name"/>
     <label name="parent"/>
     <field name="parent"/>
+    <label name="number"/>
+    <field name="number"/>
+
     <label name="type"/>
     <field name="type"/>
     <label name="company"/>
diff --git a/modules/project/view/work_list.xml b/modules/project/view/work_list.xml
index fbc01fbca3..a8949af3a1 100644
--- a/modules/project/view/work_list.xml
+++ b/modules/project/view/work_list.xml
@@ -3,6 +3,7 @@
 this repository contains the full copyright notices and license terms. -->
 <tree sequence="sequence">
     <field name="company" expand="1" optional="1"/>
+    <field name="number"/>
     <field name="rec_name" expand="1"/>
     <field name="timesheet_duration" optional="0"/>
     <field name="total_effort" optional="0"/>
diff --git a/modules/project/view/work_list_children.xml b/modules/project/view/work_list_children.xml
index 61f3ba9ad1..f77864be7a 100644
--- a/modules/project/view/work_list_children.xml
+++ b/modules/project/view/work_list_children.xml
@@ -2,7 +2,9 @@
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
 <tree sequence="sequence">
-    <field name="name" expand="1"/>
+    <field name="name" expand="1">
+        <prefix name="number"/>
+    </field>
     <field name="timesheet_duration" optional="0"/>
     <field name="total_effort" optional="0"/>
     <field name="type" optional="1"/>
diff --git a/modules/project/view/work_list_simple.xml b/modules/project/view/work_list_simple.xml
index 480a2f234e..c4734be177 100644
--- a/modules/project/view/work_list_simple.xml
+++ b/modules/project/view/work_list_simple.xml
@@ -3,6 +3,7 @@
 this repository contains the full copyright notices and license terms. -->
 <tree>
     <field name="company" expand="1" optional="1"/>
+    <field name="number"/>
     <field name="rec_name" expand="1"/>
     <field name="type" optional="1"/>
     <field name="status" optional="0"/>
diff --git a/modules/project/view/work_tree.xml b/modules/project/view/work_tree.xml
index b72f1ada63..07b106336f 100644
--- a/modules/project/view/work_tree.xml
+++ b/modules/project/view/work_tree.xml
@@ -2,7 +2,9 @@
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
 <tree sequence="sequence">
-    <field name="name" expand="1"/>
+    <field name="name" expand="1">
+        <prefix name="number"/>
+    </field>
     <field name="company" expand="1" optional="1"/>
     <field name="timesheet_duration" optional="0"/>
     <field name="total_effort" optional="0"/>
diff --git a/modules/project/view/work_tree_simple.xml b/modules/project/view/work_tree_simple.xml
index 2e5c0a3789..43e792e933 100644
--- a/modules/project/view/work_tree_simple.xml
+++ b/modules/project/view/work_tree_simple.xml
@@ -2,7 +2,9 @@
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
 <tree sequence="sequence">
-    <field name="name" expand="1"/>
+    <field name="name" expand="1">
+        <prefix name="number"/>
+    </field>
     <field name="company" expand="1" optional="1"/>
     <field name="type" optional="1"/>
     <field name="status" optional="0"/>
diff --git a/modules/project/work.py b/modules/project/work.py
index d518195fc5..fec3dce22c 100644
--- a/modules/project/work.py
+++ b/modules/project/work.py
@@ -4,17 +4,58 @@
 import datetime
 from collections import defaultdict
 
+from sql import Null
+from sql.functions import CharLength
+
 from trytond.cache import Cache
 from trytond.i18n import gettext
 from trytond.model import (
-    ChatMixin, DeactivableMixin, Index, ModelSQL, ModelView, fields,
-    sequence_ordered, sum_tree, tree)
+    ChatMixin, DeactivableMixin, Index, ModelSingleton, ModelSQL, ModelView,
+    Unique, ValueMixin, fields, sequence_ordered, sum_tree, tree)
+from trytond.modules.company.model import CompanyMultiValueMixin
 from trytond.pool import Pool
-from trytond.pyson import Bool, Eval, If, PYSONEncoder, TimeDelta
+from trytond.pyson import Bool, Eval, Id, If, PYSONEncoder, TimeDelta
+from trytond.tools import is_full_text, lstrip_wildcard
 from trytond.transaction import Transaction
 
 from .exceptions import WorkProgressValidationError
 
+_work_sequence = fields.Many2One(
+    'ir.sequence', "Work Effort Sequence", required=True,
+    domain=[
+        ('sequence_type', '=', Id('project', 'sequence_type_work')),
+        ],
+    help="Used to generate the work number.")
+
+
+class Configuration(
+        ModelSingleton, ModelSQL, ModelView, CompanyMultiValueMixin):
+    __name__ = 'project.configuration'
+
+    work_sequence = fields.MultiValue(_work_sequence)
+
+    @classmethod
+    def multivalue_model(cls, field):
+        pool = Pool()
+        if field == 'work_sequence':
+            return pool.get('project.configuration.sequence')
+        return super().multivalue_model(field)
+
+    @classmethod
+    def default_work_sequence(cls, **pattern):
+        pool = Pool()
+        ModelData = pool.get('ir.model.data')
+        try:
+            return ModelData.get_id('project', 'sequence_work')
+        except KeyError:
+            return None
+
+
+class ConfigurationSequence(ModelSQL, ValueMixin):
+    __name__ = 'project.configuration.sequence'
+
+    work_sequence = _work_sequence
+
 
 class WorkStatus(DeactivableMixin, sequence_ordered(), ModelSQL, ModelView):
     __name__ = 'project.work.status'
@@ -113,6 +154,7 @@ class Work(
             ],
         "Type", required=True)
     company = fields.Many2One('company.company', "Company", required=True)
+    number = fields.Char("Number", readonly=True)
     party = fields.Many2One('party.party', 'Party',
         states={
             'invisible': Eval('type') != 'project',
@@ -191,13 +233,25 @@ class Work(
 
     @classmethod
     def __setup__(cls):
+        cls.number.search_unaccented = False
         cls.path.search_unaccented = False
         super().__setup__()
         t = cls.__table__()
+        cls._sql_constraints += [
+            ('number_unique', Unique(t, t.number),
+                'project.msg_work_number_unique'),
+            ]
         cls._sql_indexes.update({
+                Index(t, (t.number, Index.Equality(cardinality='high'))),
+                Index(t, (t.number, Index.Similarity(cardinality='high'))),
                 Index(t, (t.path, Index.Similarity(begin=True))),
                 })
 
+    @classmethod
+    def order_number(cls, tables):
+        table, _ = tables[None]
+        return [table.number != Null, CharLength(table.number), table.number]
+
     @staticmethod
     def default_type():
         return 'task'
@@ -403,6 +457,38 @@ class Work(
             language = party.lang.code if party and party.lang else None
         return language
 
+    @classmethod
+    def search_rec_name(cls, name, clause):
+        _, operator, value = clause
+        if operator.startswith('!') or operator.startswith('not '):
+            bool_op = 'AND'
+        else:
+            bool_op = 'OR'
+        code_value = value
+        if operator.endswith('like') and is_full_text(value):
+            code_value = lstrip_wildcard(value)
+        domain = [bool_op,
+            ('number', operator, code_value),
+            ('name', operator, value),
+            ]
+        return domain
+
+    @classmethod
+    def _number_sequence(cls, **pattern):
+        pool = Pool()
+        Configuration = pool.get('project.configuration')
+        config = Configuration(1)
+        return config.get_multivalue('work_sequence', **pattern)
+
+    @classmethod
+    def preprocess_values(cls, mode, values):
+        values = super().preprocess_values(mode, values)
+        if mode == 'create':
+            if not values.get('number'):
+                if sequence := cls._number_sequence():
+                    values['number'] = sequence.get()
+        return values
+
     @classmethod
     def copy(cls, project_works, default=None):
         pool = Pool()
@@ -411,6 +497,7 @@ class Work(
             default = {}
         else:
             default = default.copy()
+        default.setdefault('number')
         default.setdefault('progress', None)
         default.setdefault(
             'status', lambda data: WorkStatus.get_default_status(data['type']))
diff --git a/modules/project/work.xml b/modules/project/work.xml
index a96d8cba23..4667ad12fd 100644
--- a/modules/project/work.xml
+++ b/modules/project/work.xml
@@ -3,6 +3,56 @@
 this repository contains the full copyright notices and license terms. -->
 <tryton>
     <data>
+        <record model="ir.ui.view" id="project_configuration_view_form">
+            <field name="model">project.configuration</field>
+            <field name="type">form</field>
+            <field name="name">project_configuration_form</field>
+        </record>
+
+        <record model="ir.action.act_window" id="act_project_configuration">
+            <field name="name">Configuration</field>
+            <field name="res_model">project.configuration</field>
+        </record>
+        <record model="ir.action.act_window.view" id="act_project_configuration_view1">
+            <field name="sequence" eval="10"/>
+            <field name="view" ref="project_configuration_view_form"/>
+            <field name="act_window" ref="act_project_configuration"/>
+        </record>
+        <menuitem
+            parent="menu_configuration"
+            action="act_project_configuration"
+            sequence="10"
+            id="menu_project_configuration"
+            icon="tryton-list"/>
+
+        <record model="ir.model.access" id="access_project_configuration">
+            <field name="model">project.configuration</field>
+            <field name="perm_read" eval="True"/>
+            <field name="perm_write" eval="False"/>
+            <field name="perm_create" eval="False"/>
+            <field name="perm_delete" eval="False"/>
+        </record>
+        <record model="ir.model.access" id="access_project_configuration_party_admin">
+            <field name="model">project.configuration</field>
+            <field name="group" ref="group_project_admin"/>
+            <field name="perm_read" eval="True"/>
+            <field name="perm_write" eval="True"/>
+            <field name="perm_create" eval="False"/>
+            <field name="perm_delete" eval="False"/>
+        </record>
+
+        <record model="ir.sequence.type" id="sequence_type_work">
+            <field name="name">Project Work Effort</field>
+        </record>
+        <record model="ir.sequence.type-res.group" id="sequence_type_work_group_admin">
+            <field name="sequence_type" ref="sequence_type_work"/>
+            <field name="group" ref="res.group_admin"/>
+        </record>
+        <record model="ir.sequence.type-res.group" id="sequence_type_work_group_project_admin">
+            <field name="sequence_type" ref="sequence_type_work"/>
+            <field name="group" ref="group_project_admin"/>
+        </record>
+
         <record model="ir.ui.view" id="work_status_view_list">
             <field name="model">project.work.status</field>
             <field name="type">tree</field>
@@ -261,6 +311,15 @@ this repository contains the full copyright notices and license terms. -->
 
     </data>
     <data noupdate="1">
+        <record model="ir.sequence" id="sequence_work">
+            <field name="name">Work Effort</field>
+            <field name="sequence_type" ref="sequence_type_work"/>
+        </record>
+
+        <record model="project.configuration.sequence" id="project_configuration_sequence">
+            <field name="work_sequence" ref="sequence_work"/>
+        </record>
+
         <record model="project.work.status" id="work_open_status">
             <field name="name">Open</field>
             <field name="default" eval="True"/>