# Connect Reverse ETL Source to Marketo Static Lists

This guide takes you through the steps to connect a Reverse ETL source to the Marketo Static Lists destination.

## Set up connection 

{{< warning >}}
**The Reverse ETL feature supports only source-driven pipeline configuration.**

Make sure you have [set up a RETL source]({{< ref "sources/reverse-etl/_index.md" >}}) and connected it to your Marketo Static Lists destination before following the below steps.
{{< /warning >}}

1. [Confirm the connection settings]({{< ref "destinations/reverse-etl-destinations/marketo-static-lists/setup-guide.md#connection-settings" >}}) for Marketo Static Lists destination and click **Continue**.
2. In the [Data Mapping]({{< ref "data-pipelines/reverse-etl/developer-guides/visual-data-mapper.md" >}}) section, select **Lead Ids** from the **Object** dropdown.
3. Set the [sync mode]({{< ref "data-pipelines/reverse-etl/developer-guides/sync-modes.md" >}}) to **Mirror**. This setting specifies how RudderStack syncs the data to Marketo.
4. In **Choose identifier**, specify the warehouse column that RudderStack uses to identify your records. You can map this warehouse column to the **Lead Id** destination field.

## Considerations for sending data

Note the following while syncing data from your warehouse to Marketo:

- The data to be synced to Marketo as the **Lead ID** needs to be an integer or string that can be cast to a number. Otherwise, you will get an error.
- The lead ID should already be present in Marketo as the Marketo Static Lists destination can only add or remove a lead from the list.

## FAQ

#### Why can't I add a Reverse ETL source from the destination page?

The Reverse ETL feature supports only source-driven pipeline configuration. It means that you must configure a Reverse ETL source in RudderStack and then connect it to a new or existing destination. Note that this destination should not be connected to any other source.

See [Reverse ETL FAQ]({{< ref "data-pipelines/reverse-etl/developer-guides/faq.md" >}}) for more information.

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