A condominium apartment owner buys a piece of real property in a legal subdivision - and holds title to a specific unit within a building. Cooperative apartment owners, on the other hand, own a share of stock in a corporation and the right to occupy a certain apartment. The corporation owns the structure that contains the unit.

Condominium owners can arrange their own financing and often do, but cooperatives have blanket mortgages on the entire building. As a consequence, if you need to borrow to buy a cooperative, you generally have to persuade the seller of the apartment to carry the loan. Lending agencies in Washington rarely are willing to finance individual co-op units because the loan can be secured only by stock, not a lien on real property. Moreover, few cooperatives permit investor-owners, so a lender cannot resell an apartment to an investor in the event of foreclosure and, usually, must secure the cooperative's approval of any buyer it might find for the unit. The fledgling D.C. Cooperative Housing Association is currently working on a set of recommendations to the city's lending agencies to try and remedy the financing problems.

Maintenance fees vary in condominiums and cooperatives depending on the cost of shared services and range from less than $100 to $1,000 a month. Some smaller coops are self-managing, in order to keep monthly costs to a minimum.