The development of contact lenses has been guided, in large measure, by the effort to produce lens materials that provide sufficient oxygen to the cornea. The prime obstacle to those efforts has been that attainment of high oxygen transmissibility has necessitated the compromise of other essential properties, such as wettability and resistance to deposits. This article reviews the history and current status of efforts to manufacture a lens material that will provide a balance among all of these properties. In addition, consideration is given to the complications associated with extended wear of contact lenses and practical ways of minimizing those complications, even in the absence of a lens material that is ideally suited for this purpose.