BPMN pools and lanes explained

By Emilis Mikalajūnas · Published July 8, 2026

Pools and lanes are BPMN's swimlanes: they show who does what. A pool is a whole participant (an organisation, system, or major role) containing a complete process; a lane is a subdivision inside a pool — a specific person, team or department. Together they turn a flat list of steps into a clear picture of responsibility and hand-offs.

Lanes — who performs each step

Within one process (one pool), lanes split the work by role. An invoice-approval process might have three lanes:

• Employee — submits the invoice.
• Manager — approves or rejects.
• Finance — schedules payment.

Each task sits in the lane of whoever performs it, so a reader instantly sees the hand-offs. Sequence flows (solid arrows) move freely between lanes because it's all one process.

Pools — separate participants

Use separate pools when two independent parties each run their own process and only communicate by exchanging messages. Classic example: a Customer pool and a Supplier pool in an ordering process. Each pool has its own start and end; neither controls the other's internal steps.

The critical rule: sequence flow vs message flow

This is the rule beginners most often break:

• Sequence flow (solid arrow) — connects steps within a single pool. It never crosses a pool boundary.
• Message flow (dashed arrow) — connects different pools. It represents communication (an order sent, a confirmation returned).

If you find yourself drawing a solid arrow from one pool into another, it should be a dashed message flow instead. See common BPMN mistakes.

Collapsed pools (black boxes)

Sometimes you only care that a message goes to an external party, not what they do with it. Draw that party as a collapsed pool — an empty rectangle — and connect to it with a message flow. It says "this participant exists and we talk to them" without modelling their internals.

When do you actually need pools and lanes?

• One team, one process: a single pool with lanes is usually enough (and often you can skip the pool border entirely).
• Two organisations interacting: multiple pools with message flows.
• A quick internal sketch: you can often omit swimlanes and just use tasks and flows.

Deciding lane assignments and message flows by hand takes practice. Describe the participants in plain English — "HR submits the request, IT provisions accounts, the manager assigns a buddy" — and BPMN Studio will place the tasks in the right lanes for you. Next: the full symbol reference or how to create a BPMN diagram.