Each generation has its own prevailing view of the office of the American presidency. Recently we shuddered before the ogre of the "imperial presidency." Now we complain-to quote the author of this up-to-date and informed study-that "Presidents remain too weak to manage most problems until they get out of hand." Pious points to the President's constitutional prerogatives as the key to his power. It is by exercising these prerogatives that the President sets the agenda to which the other parts of the system react. Here is a post-Watergate book, a first-rate analysis of the present rather than a doleful autopsy.