Theodore Aloysius "Theo" Huxtable (Malcolm-Jamal Warner), is the only son of Cliff and Clair Huxtable, and is athletic and obsessed with impressing girls, and obtaining a sports car or motorcycle. He is fourteen years old when the series begins, making his birth year 1970. In the pilot episode, he is lectured by his father for not applying himself at school ("I brought you in this world, and I'll take you out"). Also in the early seasons, he was somewhat of a troublemaker, as illustrated through incidents both alluded to and explicitly portrayed in the series, but his behavior had improved by the time he left high school.
A running theme of the early seasons revolved around Theo's academic struggles, especially in his sophomore-year geometry class, taught by Mrs. Westlake. As the seasons progressed, Theo gradually evolved from being an under-achiever to a successful high school - and college - student (in interviews, Cosby noted a similar change in his real-life son, Ennis). While Theo was a student at NYU, it was revealed that he suffered from dyslexia, a learning disability that inspired him to work harder, and as a result overcame it. By the final season, Theo was a student teacher, helping other children with dyslexiaat a local education center. In the show's final episode, he graduated from NYU with a degree in psychology.
In the pilot, and once more in Season 1, (an episode entitled "Bad Dreams"), he is referred to by Vanessa as "Teddy", instead of "Theo."
Theo has a long-running, but on-and-off relationship with a girl named Justine, who is mentioned many times throughout the series, but appears in only nine episodes. During his high school years, Theo's best friend was Walter Bradley, better known as "Cockroach", who was more of a scholastic underachiever than Theo. The two of them would occasionally compose rap songs for various school assignments. When Theo got tickets to "Dance Mania" (a Soul Train-like television dance show), and only one of them was allowed into the studio, Theo let Cockroach have the spot, but did not feel good about it when he saw Cockroach on TV, and as the center of their friends' attention the next day at school.