Perhaps the most significant of several producers who reshaped American television in the 1970s, Norman Lear brought his particular genius to the situation comedy genre. Infusing sitcom content with social commentary and earthy language while also updating its visual form with the immediacy of live videotaping, Lear created a string of shows—All in the Family, Sanford and Son, Maude, The Jeffersons, One Day at a Time, Mary Hartman, Mary Hartman —that captured national audiences as effortlessly as they did the zeitgeist.

Lear's career began almost by accident. A salesman by day and gagwriter by night, Lear sold a routine to Danny Thomas that resulted in an offer to write for The Ford Star Revue in 1951. He moved on to work as a writer for Dean Martin and Jerry Lewis on The Colgate Comedy Hour, followed by similar jobs with other variety shows. By...