# Child Workflows - Ruby SDK

> Start a Child Workflow Execution and set a Parent Close Policy using Temporal Ruby SDK.

This page shows how to do the following:

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

## Start a Child Workflow Execution 

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 Ruby, calling `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 returns.

To spawn a Child Workflow Execution in Ruby, use the `execute_child_workflow` method which starts the Child Workflow and waits for completion or
use the `start_child_workflow` method 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 method for `start_child_workflow(...).result`.
>

```ruby
Temporalio::Workflow.execute_child_workflow(MyChildWorkflow, 'my-workflow-arg')
```

## 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 for `execute_child_workflow` or `start_child_workflow` to specify the behavior of the Child Workflow when the Parent Workflow closes.

```ruby
Temporalio::Workflow.execute_child_workflow(
  MyChildWorkflow,
  'my-workflow-arg',
  parent_close_policy: Temporalio::Workflow::ParentClosePolicy::ABANDON
)
```