The Capabilities System describes the totality of organizational abilities needed to execute a chosen strategy. It is not about individual competencies but about their interplay: capabilities must reinforce each other and function as an integrated system. A consistently built capabilities system is far harder for competitors to copy than any single capability.
IKEA exemplifies a coherent capabilities system: design competence (Scandinavian design at low cost), flat-pack logistics (efficient storage and transport), purchasing power (global sourcing of large volumes), and store concept (self-service combined with experiential dining) mesh seamlessly. Any one of these capabilities alone would be copyable, but the system as a whole is nearly impossible to replicate. A competitor that copies only the logistics without the design concept and the store experience will fail.
The concept comes from the Playing-to-Win framework by Lafley and Martin. The central test question is: Do our capabilities reinforce each other, or are they disconnected individual abilities? Only in the first case does a sustainable strategic advantage emerge.