# Connect Reverse ETL Source to Criteo Audience

This guide takes you through the steps to connect a Reverse ETL source to the Criteo Audience destination. You can also create a new Audience Segmentor use an existing Audience Segment while setting up the connection.

## Connection setup

The below steps assume that you have already [set up a RETL source]({{< ref "sources/reverse-etl/_index.md" >}}) and chosen Criteo Audience as the corresponding destination.

1. [Configure the connection settings]({{< ref "destinations/reverse-etl-destinations/criteo-audience/setup-criteo-audience.md#connection-settings" >}}) for Criteo Audience.
2. Enter the **Advertiser ID** from your Criteo URL, where all the audiences are listed. For example, in this sample Criteo URL `https://marketing.criteo.com/audience-manager/list/audiences?advertiserId=1234`, the advertiser ID is `1234`.

{{< image src="images/event-stream-destinations/criteo-advertiser-id.webp" >}}

3. In the **Where do you want to sync data to?** section:

    - Select **Create New audience** to create a new Audience Segment (of type [Contact List](https://developers.criteo.com/marketing-solutions/v2025.01/docs/audience-segments#contact-list)) in Criteo. Specify the name and description of the audience in the respective fields.

    {{< image src="images/event-stream-destinations/fb-custom-audience-new.webp" >}}

    - Select **Use Existing Audience** if you have an existing Audience Segment (of type [Contact List](https://developers.criteo.com/marketing-solutions/v2025.01/docs/audience-segments#contact-list)) and specify the [Audience Segment ID](#audience-segment-id-for-existing-audience).

    {{< image src="images/event-stream-destinations/fb-custom-audience-existing.webp" >}}

4. Configure the remaining settings as required to set up the connection successfully.

If you have selected **Create New audience** option in Step 3, the new Audience Segment will be created for that particular advertiser ID with the same **Audience ID** as in the **Schema** tab of your Reverse ETL connection.

{{< image src="images/retl-sources/audience-id.webp" >}}

## Audience segment ID for using an existing audience {#audience-segment-id-for-existing-audience}

To use an existing audience from Criteo, make sure that it is created as a [Contact List Audience Segment](https://developers.criteo.com/marketing-solutions/v2025.01/docs/audience-segments#contact-list) and not directly in the dashboard. Follow these steps:

1. Authenticate yourself by [generating an access token](https://developers.criteo.com/marketing-solutions/docs/authentication#generate-an-access-token) with your API credentials to use the Criteo API.
2. Create a new [Contact List Audience Segment](https://developers.criteo.com/marketing-solutions/docs/audience-segments#create-audience-segments) by making a POST call.

The Criteo API returns a unique Audience Segment ID associated with the newly created Audience Segment. You can use this ID in the **Use Existing Audience** section in the RudderStack dashboard.

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