3PL, 4PL, or LLP? The question of definitions and distinctions among them is highly controversial both in practice and theory. Logistics outsourcing is one of the most discussed logistics topics of the last decade. While logistics services in the 1970s were still limited to traditional transport, handling, and storage activities, today comprehensive system services are expected from customers. Within these system services, logistics providers take on the integration of various value creation stages, which can be upstream or downstream, and perform planning, control, coordination, optimization, and monitoring tasks. Logistics providers increasingly rely on information technologies and structure the entire value chain and corporate network.