Frank Bunker Gilbreth (Clifton Webb) and Lillian Gilbreth (Myrna Loy) are the parents of twelve children, six boys and six girls in the 1920's. Frank and Lillian are motion study experts who use their children as test subjects for their theories. In one instance, Frank uses the opportunity of his children having their tonsils taken out to test his theories about medical practice. At the same time, the children, particularly the two eldest Anne (Jeanne Crain) and Ernestine (Barbara Bates), are constantly trying to rebel against Frank's extremely old-fashioned beliefs about the way people should dress and act.