When "The Carol Burnett Show" made its network debut on CBS-TV on September 11, 1967, it was scheduled on Mondays at 10:00 pm (EST) opposite NBC’s "I Spy" and ABC’s "The Big Valley". At the end of its first season and through the spring of 1971, it consistently ranked among the top-30 programs. (For the 1969–70 season, it posted its highest rating ever, ranking at number 13.) For season five, CBS moved the show to Wednesdays at 8:00 pm (EST), where its chief competition was NBC’s "Adam-12" and the ABC sitcoms "Bewitched" and "The Courtship of Eddie's Father". Despite the schedule change, the show continued to do well until the fall of 1972, when the ratings slipped. In December 1972, CBS again moved "The Carol Burnett Show" to Saturdays at 10:00 pm (EST) where, for the next four years, it not only received solid ratings, but was also part of a powerhouse Saturday-night lineup of primetime shows that included "All in the Family", "M*A*S*H", "The Mary Tyler Moore Show", and "The Bob Newhart Show".