# Start a care flow
URL: https://docs.awellhealth.com/api-reference/guides/start-a-care-flow

> For the complete documentation index, see [llms.txt](https://docs.awellhealth.com/llms.txt).



Reference for the mutations themselves is in [Care flows](/api-reference/reference/care-flows). This page
covers what you need to know around them.

## Prerequisites [#prerequisites]

**A care flow can only be started for a patient, so create the patient first.** See
[Patients](/api-reference/reference/patients).

Creating a patient returns an Awell patient ID. If you created the patient using your own business
identifiers, you can start a care flow with those instead, which means your system never has to store an
Awell ID. Identifiers must be set up at tenant level first. See
[Patient identifiers](/docs/connect-systems/patient-identifiers).

## Which start mutation [#which-start-mutation]

The two mutations differ only in how the patient is identified:

| Mutation                            | Identifies the patient by        |
| ----------------------------------- | -------------------------------- |
| `startPathway`                      | The Awell patient ID             |
| `startPathwayWithPatientIdentifier` | One of your business identifiers |

Prefer the identifier version if your system is the source of truth for patients; it removes a whole
class of "which ID is this" bugs.

## Which version starts [#which-version-starts]

**Awell automatically starts the most recent published version** of the care flow definition.

You can pass a `release_id` to start a specific version instead. A patient stays on the version they
started on for the life of their care flow, so the version passed at start determines their experience
months later. See
[Versions and releases](/api-reference/guides/versions-and-releases).

## Baseline data at start [#baseline-data-at-start]

If the care flow defines required baseline data points, supply them at start or the request is rejected.

If the care flow's logic reads an optional baseline data point and the value is missing, the flow halts
at that logic with no error. See
[Enrich your care flow with baseline data](/docs/design-care-flows/enrich-your-care-flow-with-baseline-data).

## Starting a hosted-pages session at the same time [#starting-a-hosted-pages-session-at-the-same-time]

If a patient should immediately interact with their first activity, one mutation both starts the care
flow and returns a hosted-pages session URL. Use it for self-enrollment, where the person is present and
waiting.

See [Hosted sessions](/api-reference/reference/hosted-sessions), and
[Trigger with a Hosted Pages link](/docs/automate-with-events/trigger-with-a-hosted-pages-link) for the
no-code equivalent.

**Sessions expire.** Generate the session at the moment you hand the patient over, not in advance.

## Next steps [#next-steps]

**Next:** [Query activities](/api-reference/guides/query-activities) to find out what the care flow
produced.