Business processes are conventionally modeled as monolithic flows that capture the desired business logic. However, developing process flows is challenging. Because a flow specifies what its participants should do, it restricts the autonomy of its participants, thus limiting their ability to exploit opportunities or accommodate exceptions according to their business preferences. We take a dual perspective wherein business processes are modeled as compositions of (instantiated) business protocols. Each business protocol specifies interactions among its partners; each protocol serves a unique business purpose, e.g., processing a payment or shipping an item. Thus, modularizing a monolithic business process via business protocols allows clear separation of concerns for modeling and enacting the process. We develop an approach in which protocols are compiled into local skeletal flows for each participant that can be fleshed out with local business logic as needed. Such flows are naturally distributed but can be enacted using commercial business flow engines. Thus, our protocol-based approach combines the benefit of improved modeling with simplified implementations.