Pioneers of Television Season 4

This star-packed episode features fresh interviews with Jerry Seinfeld, Roseanne Barr, Tim Allen, Ray Romano and Bob Newhart. The program reveals how America's top standup comics made the transition to the sitcom format and includes dozens of clips from "Seinfeld," "Home Improvement," "Everybody Loves Raymond," "Roseanne" and more.

From George Clooney on "ER" to Richard Chamberlain on "Dr. Kildare," television's long love affair with doctors and nurses shows no signs of letting up. Noah Wyle, Anthony Edwards, Gloria Reuben and Eriq LaSalle open up about the secrets of "ER"; Howie Mandel, Ed Begley Jr. and Christina Pickles revisit "St. Elsewhere." The episode also features the final interview with Chad Everett of "Medical Center".

This episode traces the story of people of color on American television -- including the mid-1960s breakthroughs of African Americans Diahann Carroll ("Julia") and Bill Cosby ("I Spy"). Latino landmarks range from "I Love Lucy" with Desi Arnaz to "Miami Vice" with Edward James Olmos. Also featured are Asian-Americans like George Takei ("Star Trek"), who details his youth spent in a Japanese internment camp.

The backstage techniques of comic actors, including Robin Williams, Jonathan Winters and Tina Fey.