Ownership in a Cooperative Building (Co-op) is slightly different than ownership of a Condominium. Cooperative buildings pre-existed the change in real estate law that allowed for the division of land needed for Condominiums to be real estate. In a Co-op you purchase shares of a corporation which sole purpose is to manage the building. Like most corporations the Catalpa-Winthrop Building Corporation is managed by a board of directors with the assistance of a professional real estate management company. The board is elected annually by a vote of all share holders.