# Child Workflows - Python SDK

> Start a Child Workflow Execution and set a Parent Close Policy using the Temporal Python SDK. Ensure proper progress logging and specify Parent Workflow behavior upon closure.

This page shows how to do the following:

- [Start a Child Workflow Execution](#child-workflows)
- [Set a Parent Close Policy](#parent-close-policy)

## Start a Child Workflow Execution 

**How to start a Child Workflow Execution using the Temporal Python SDK.**

A [Child Workflow Execution](/child-workflows) is a Workflow Execution that is scheduled from within another Workflow using a Child Workflow API.

When using a Child Workflow API, Child Workflow related Events ([StartChildWorkflowExecutionInitiated](/references/events#startchildworkflowexecutioninitiated), [ChildWorkflowExecutionStarted](/references/events#childworkflowexecutionstarted), [ChildWorkflowExecutionCompleted](/references/events#childworkflowexecutioncompleted), etc...) are logged in the Workflow Execution Event History.

The [ChildWorkflowExecutionStarted](/references/events#childworkflowexecutionstarted) Event must be logged to the Event History before the Parent Workflow completes to ensure the Child Workflow has started.
In Python, awaiting `start_child_workflow()` or `execute_child_workflow()` internally waits for this Event before returning, so the Child Workflow is guaranteed to have started once the call resolves.
If you start a Child Workflow from a non-main coroutine (for example, a Signal or Update handler), make sure the Parent Workflow doesn't complete before that call resolves.

To spawn a Child Workflow Execution in Python, use the [`execute_child_workflow()`](https://python.temporal.io/temporalio.workflow.html#execute_child_workflow) function which starts the Child Workflow and waits for completion or
use the [`start_child_workflow()`](https://python.temporal.io/temporalio.workflow.html#start_child_workflow) function to start a Child Workflow and return its handle.
This is useful if you want to do something after it has only started, or to get the Workflow/Run ID, or to be able to signal it while running.

> **📝 Note:**
>
> `execute_child_workflow()` is a helper function for `start_child_workflow()` plus `await handle`.
>

<div className="copycode-notice-container">
  <a href="https://github.com/temporalio/documentation/blob/main/sample-apps/python/your_child_workflow/your_child_workflow_dacx.py">
    View the source code
  </a>{' '}
  in the context of the rest of the application code.
</div>

```python
# ...
@workflow.defn
class ComposeGreetingWorkflow:
    @workflow.run
    async def run(self, input: ComposeGreetingInput) -> str:
        return f"{input.greeting}, {input.name}!"

@workflow.defn
class GreetingWorkflow:
    @workflow.run
    async def run(self, name: str) -> str:
        return await workflow.execute_child_workflow(
            ComposeGreetingWorkflow.run,
            ComposeGreetingInput("Hello", name),
            id="hello-child-workflow-workflow-child-id",
# ...
        )
```

### Set a Parent Close Policy 

**How to set a Parent Close Policy**

A [Parent Close Policy](/parent-close-policy) determines what happens to a Child Workflow Execution if its Parent changes to a Closed status (Completed, Failed, or Timed Out).

The default Parent Close Policy option is set to terminate the Child Workflow Execution.

Set the `parent_close_policy` parameter inside the [`start_child_workflow`](https://python.temporal.io/temporalio.workflow.html#start_child_workflow) function or the [`execute_child_workflow()`](https://python.temporal.io/temporalio.workflow.html#execute_child_workflow) function to specify the behavior of the Child Workflow when the Parent Workflow closes.

<div className="copycode-notice-container">
  <a href="https://github.com/temporalio/documentation/blob/main/sample-apps/python/your_child_workflow/your_child_workflow_dacx.py">
    View the source code
  </a>{' '}
  in the context of the rest of the application code.
</div>

```python
from temporalio.workflow import ParentClosePolicy
# ...
# ...
@workflow.defn
class ComposeGreetingWorkflow:
    @workflow.run
    async def run(self, input: ComposeGreetingInput) -> str:
        return f"{input.greeting}, {input.name}!"

@workflow.defn
class GreetingWorkflow:
    @workflow.run
    async def run(self, name: str) -> str:
        return await workflow.execute_child_workflow(
            ComposeGreetingWorkflow.run,
            ComposeGreetingInput("Hello", name),
            id="hello-child-workflow-workflow-child-id",
            parent_close_policy=ParentClosePolicy.ABANDON,
        )
```