> ## Documentation Index > Fetch the complete documentation index at: https://docs.monaco.com/llms.txt > Use this file to discover all available pages before exploring further. # Enroll Contacts in a Campaign > Enrolls contacts into a campaign by creating a new audience named `audience_name`, attaching it to the campaign, and adding the contacts to it. The campaign must be `active` or `paused`. Sequences are created asynchronously; contacts already enrolled in the campaign are deduplicated then and still count as successes here. This always creates a new audience. Before calling this tool, if the campaign already has audiences, you MUST ask the user whether to create a new audience or add the contacts to an existing one via `add_contacts_to_audience` — and warn them that audiences can be shared, so adding contacts to a shared audience enrolls them in every campaign that uses it. ## OpenAPI ````yaml https://api.monaco.com/openapi.json post /v1/campaigns/{campaign_id}/enroll openapi: 3.1.0 info: title: Monaco Public API description: Public API for Monaco version: 1.0.0 servers: - url: https://api.monaco.com security: [] paths: /v1/campaigns/{campaign_id}/enroll: post: tags: - Campaigns summary: Enroll Contacts in a Campaign description: >- Enrolls contacts into a campaign by creating a new audience named `audience_name`, attaching it to the campaign, and adding the contacts to it. The campaign must be `active` or `paused`. Sequences are created asynchronously; contacts already enrolled in the campaign are deduplicated then and still count as successes here. This always creates a new audience. Before calling this tool, if the campaign already has audiences, you MUST ask the user whether to create a new audience or add the contacts to an existing one via `add_contacts_to_audience` — and warn them that audiences can be shared, so adding contacts to a shared audience enrolls them in every campaign that uses it. operationId: enroll_contacts_in_campaign parameters: - name: campaign_id in: path required: true schema: type: string format: uuid title: Campaign Id requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/EnrollContactsInCampaignRequest' responses: '200': description: Successful Response content: application/json: schema: $ref: >- #/components/schemas/PublicItemResponse_EnrollContactsInCampaignResponse_ example: data: success_count: 3 failure_count: 1 failure_reasons: - code: contact_not_found description: contact not found count: 1 meta: timestamp: '2026-07-09T10:30:00Z' '400': description: Campaign is not enrollable or the audience name is taken content: application/json: schema: $ref: '#/components/schemas/PublicErrorResponse' '404': description: Campaign not found content: application/json: schema: $ref: '#/components/schemas/PublicErrorResponse' 4XX: description: Client error content: application/json: schema: $ref: '#/components/schemas/PublicErrorResponse' components: schemas: EnrollContactsInCampaignRequest: properties: audience_name: type: string maxLength: 255 minLength: 1 title: Audience Name description: >- Name for the new audience created to hold these contacts; pick something short and relevant to the enrollment. Must be unique within the organization — a duplicate name is rejected, so vary it and retry. examples: - Q3 Enterprise Outbound — July batch contact_ids: items: type: string format: uuid type: array maxItems: 10000 minItems: 1 title: Contact Ids description: IDs of the contacts to enroll in the campaign examples: - - 550e8400-e29b-41d4-a716-446655440020 type: object required: - audience_name - contact_ids title: EnrollContactsInCampaignRequest PublicItemResponse_EnrollContactsInCampaignResponse_: properties: data: $ref: '#/components/schemas/EnrollContactsInCampaignResponse' meta: $ref: '#/components/schemas/ResponseMeta' type: object required: - data title: PublicItemResponse[EnrollContactsInCampaignResponse] PublicErrorResponse: properties: error: $ref: '#/components/schemas/ErrorDetail' type: object required: - error title: PublicErrorResponse EnrollContactsInCampaignResponse: properties: success_count: type: integer title: Success Count description: Contacts added to the campaign's new audience examples: - 2 failure_count: type: integer title: Failure Count description: >- Contacts that could not be added (e.g. not found in the organization) examples: - 1 failure_reasons: items: $ref: '#/components/schemas/EnrollFailureReason' type: array title: Failure Reasons description: Failure reasons with the number of contacts affected by each type: object required: - success_count - failure_count title: EnrollContactsInCampaignResponse description: |- Aggregate outcome of enrolling contacts into a campaign. Counts reflect contacts added to the campaign's new audience. Sequence creation happens asynchronously, so contacts already enrolled in the campaign are deduplicated later and still count as successes here. ResponseMeta: properties: timestamp: type: string format: date-time title: Timestamp description: Server timestamp of the response type: object title: ResponseMeta ErrorDetail: properties: code: type: string title: Code description: Machine-readable error code examples: - not_found message: type: string title: Message description: Human-readable error message examples: - Resource not found type: object required: - code - message title: ErrorDetail EnrollFailureReason: properties: code: type: string title: Code description: Failure reason code (e.g. contact_has_active_sequence,) examples: - contact_has_active_sequence description: type: string title: Description description: Human-readable description of the failure reason examples: - existing active sequence count: type: integer title: Count description: Number of contacts that hit this failure examples: - 1 type: object required: - code - description - count title: EnrollFailureReason description: A categorized enrollment failure with the count of affected contacts. ````