Hardware-Software partitioning is an important phase in the design of Embedded Systems. Decisions made during this phase impact the quality, cost, performance and the delivery date of the final product. A majority of existing approaches operate at a relatively fine granularity which presents problems if the context is families of products with frequent release of upgraded or new members. Designing using a higher coarser-level granularity imposes component integration and replacement problems during system evolution and new product release. A new approach termed Concept-Based Design (CBD) is presented that focuses on System Evolution, Product Lines and large scale reuse. Beginning with information from UML 2.0 sequence diagrams and a Concept Repository, Concepts, the fundamental units of reuse in the CBD, are identified within a specification, which are then used to assemble large systems. Change localization during system evolution, composability during large-scale reuse and provision for configurable feature variations for a product line are facilitated by a Generic Adaptive Layer (GAL) created around selected concepts.