President-Elect John F. Kennedy was determined to project a wholesome, healthy image to the nation. So, on January 3, 1961, he posed with his young family for Richard Avedon. Robert Dallek tells how the photos—many published here for the first time—helped position an American dynasty. Plus: candid moments from the diaries of White House insider Arthur M. Schlesinger Jr. Web exclusive: The Kennedys: An archive of classic articles, photographs, and video from Vanity Fair and VF.com