The importance and benefits of expertise sharing for organizations in knowledge economy are well recognized. However, the potential cost of expertise sharing is less well understood. This paper proposes a conceptual framework called collective attention economy to identify the costs associated with expertise sharing and provide the basis for analyzing and understanding the cost-benefit structure of different communication mechanisms. To demonstrate the analytical power of the conceptual framework, the paper describes a new communication mechanism-Dynamic Mailing List (DML)--that is developed by adjusting certain cost factors.