Born Don Agrati in San Diego, California, Don Grady became a Mousekeeter, along with 23 others, when that show debuted in 1955. In 1960, he joined My Three Sons (1960), which debuted in 1960 and ran for 12 years. As an enthusiast of music after "My Three Sons" ended, he continued in music as a composer and songwriter. One of his songs was the theme for The Phil Donahue Show (1967). Don appeared in many other shows as a guest star but he will always be known as "Robbie Douglas", the middle son from "My Three Sons". The show ran for 12 years and 356 episodes.