Rule 415 allows a firm to register all the securities it reasonably expects to sell over the next two years and then, at the management's option, to sell those securities over these two years whenever it chooses. This paper examines whether equity offerings made under Rule 415 (shelf offerings) differ in issuing costs from equity offerings not sold under this rule. We find that shelf offerings cost 13% less for syndicated issues and 51% less for nonsyndicated issues. We also investigate the empirical relevance of the market overhang argument which suggests that shelf registrations depress the price of the registering firm's shares more than traditional registrations. Our data does not support the market overhang argument.