---
title: "Third-Party Targeting: Custom Third-Party Audiences"
slug: "ingesting-custom-third-party-audiences"
description: "Leverage LiveRamp’s Data Marketplace with Quantcast to target custom third-party audience segments effectively for your U.S. campaigns."
tags: ["Audience", "Third Party"]
updated: 2026-09-11T16:27:32Z
published: 2026-09-11T16:27:32Z
canonical: "help.quantcast.com/ingesting-custom-third-party-audiences"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://help.quantcast.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Third-Party Targeting: Custom Third-Party Audiences

Quantcast leverages **LiveRamp’s Data Marketplace** to ingest custom third-party audience segments for campaigns targeting users in the **United States**.

A **custom third-party (3P) audience** is a segment built by a third-party data provider using criteria tailored to meet a specific advertiser’s goals. These segments can be composed of:

- A unique combination of multiple off-the-shelf third-party audiences
- A single or multiple third-party audiences that have been modified directly by the data vendor (e.g., increasing the look-back window or adding additional criteria not normally used in the off-the-shelf versions)
- A blend of third-party data with the advertiser’s first-party data

> [!NOTE]
> **Third-party segments are best used as a complement to Quantcast audiences and should be viewed as a backup option when Quantcast audience targeting does not fully align with your campaign needs.**

## Ingesting Custom Third-Party Audiences

To ingest custom third-party Liveramp segment(s) onto the Quantcast platform:

Please create a custom segment in LiveRamp and include Quantcast’s Platform ID in the 'Allowed Platforms' column of their metadata file.

Note: Do NOT Distribute the file to Quantcast via the Liveramp tiles.

Then, contact your Quantcast Account Team representative and provide the **Liveramp segment ID**, **segment name**, and your account **p-code**. The Quantcast Account team will, in turn, work internally to bring the segment(s) into the marketers’ specific p-code account.

Custom third-party audience segments should appear in the marketer’s account within 24-48 hours after being assigned to the marketer’s specific account p-code.

**Note:** The above process is only for **Liveramp third-party custom segments**. For standard first-party segments, please refer to the [appropriate documentation](/v1/docs/dmp-audiences).

## How to Determine the Size of a Custom Third-Party Audience

At this time, custom third-party audience sizes can be estimated at the ad set level within a mock ad set.

1. Create a mock ad set within your account.
2. Navigate to the ad set setup level:
  1. If you have a budget and date range in mind, you can enter them to generate a delivery forecast. Otherwise, if you're only looking to view the segment’s maximum audience size, proceed to the next step.
  2. Scroll down to the **Audience** section.
  3. Remove all selections in the **Lookalike** field. This field should be left empty.
  4. Clear all entries in the **Retargeting** field.
  5. Search for and select the desired custom third-party audience within the Retargeting field. This should be the only segment listed here.
    1. **TIP:** The quickest way to find your ingested custom third-party audience is to search for it by its **Segment ID**.
  6. Navigate to the **Projections** tool on the right side of the screen and expand the audience details by clicking on the arrow (carrot icon).
  7. The **Targetable Audience** size listed reflects the size of your selected audience.
    1. **Heads Up!** If the targetable audience size appears as 100, it typically indicates that the segment contains no active data. This may be due to an issue during ingestion or a lack of available data. Please contact the data vendor and your Quantcast representative for assistance.

![](https://cdn.us.document360.io/9a180fa0-df3b-4942-a5f6-b3905cf917d9/Images/Documentation/image(19).png?sv=2026-02-06&spr=https&st=2026-11-08T07%3A51%3A40Z&se=2026-11-08T08%3A51%3A40Z&sr=c&sp=r&sig=avTu0A4%2FQ6sdGc8PPdNSchgzKdZhcBiGv5rUg7qkeVM%3D)

## Activating Your Custom Third-Party Audience

1. Navigate to the Ad Set setup within your campaign.
2. Scroll down to the **Audience** section within the Ad Set setup.
3. Based on your targeting strategy, search for and select your ingested custom third-party audience in the appropriate field(s): Lookalike, Retargeting, and/or Exclusions.
  1. **TIP:** The quickest way to find your ingested custom third-party audience is by searching by its **Segment ID**.

## Related

- [Third-Party Targeting: Off-The-Shelf Third-Party Audiences](/using-third-party-audiences.md)
- [Third-Party Audience Targeting](/third-party-targeting.md)
- [Client First-Party Data Onboarding Options](/dmp-audiences.md)