One of Mark Goodson and Bill Todman's longest-running panel game shows, "What's My Line?" aired for 25 years, in two different versions.
Both versions worked the same way: a contestant would walk out from backstage and sign his or her name on a blackboard, then sit down next to the host. Then the four panelists would try to guess the contestant's occupation by asking questions that could be answered yes or no. The same panelist could keep asking questions as long as they were getting "yes" answers. If the contestant answered "no," the next panelist in line would begin asking questions. Ten "no" answers ended the game.
In addition to the regular contestants, each episode featured a celebrity, known as the Mystery Guest. The panel would blindfold themselves before the Mystery Guest's entrance and then try to guess their name rather than their occupation. The celebrity would usually attempt to disguise their voice. Throughout most of the run of "What's My Line?", the panelists would only ask one question at a time regardless of whether the answer was "yes" or "no" before the next panelist was up.
The first version premiered on the CBS network on February 16, 1950, with host John Charles Daly. By October of that year, it was airing Sunday nights at 10:30 Eastern time, the time slot it held until the final episode aired on September 3, 1967.
The show generally aired live, although it was sometimes tape delayed, especially during the summer months.
The regularly appearing panelists on this version were Random House publisher Bennett Cerf, TV and radio host/actress Arlene Francis, and columnist Dorothy Kilgallen. Also appearing frequently on the panel were comedians Fred Allen, Johnny Carson, and Steve Allen, who, in trying to determine what product a contestant's occupation was associated with, came up with the question "Is it bigger than a breadbox?"
The other catchphrases "What's My Line?" gave to the English language were "Will the mystery guest please sign in?" and, when a panelist received a "no" answer, "That's one down and nine to go," "That's two down and eight to go," et cetera.
The second version of "What's My Line?" aired in daily syndication from 1968 until 1975. It was hosted by Wally Bruner until 1972, when he was replaced by actor Larry Blyden.
The regular panelists on the syndicated version were Arlene Francis and comedian Soupy Sales. Also appearing frequently on the panel were singer Dana Valeri, game show host Gene Rayburn, and movie critic Gene Shalit.
On this version, the "Who's Who" game was added; four audience members with differing occupations were brought on stage, each one holding up a card with one of the group's occupations printed on it. One at a time, each panelist would try to rearrange the cards so each person was holding their own job. If the panelists failed, all four audience members won luggage.
The syndicated version was less urbane and genteel than the network version, and the panelists would often have to participate in demonstrations related to a contestant's occupation, such as ice cream tastings or trying to set up a folding beach chair.
Soupy Sales turned out to be so good at guessing the identity of the mystery guest that producer Gil Fates had to implement a rule that an incorrect guess would disqualify a panelist for the rest of the segment in order to discourage him from making guesses and let the game go on longer. From then on, before the mystery guest signed in, the host would announce "Fates' Law prevails."
Both versions originated from New York.
Most of the network episodes were preserved on kinescope film, and all of the episodes of the syndicated version were preserved on color videotape. Both have been seen in reruns on Game Show Network.