Anthony commuted to Towson Catholic High School for his first three years of high school. During the summer of 1999, Anthony grew five inches into the frame of a 6–5 swingman. He suddenly became one of the area's top players and made a name for himself in the area, being named The Baltimore Sun's metro player of the year in 2001, as well as Baltimore Catholic League player of the year. During his sophomore year, he averaged 14 points, 5 rebounds, 4 assists and 2 steals. Towson Catholic surged to a record of 26–3 and finished third in the state tournament. Anthony enjoyed a successful high school basketball career as a junior, almost doubling his numbers in scoring and rebounds, averaging 23 points and 10. 3 rebounds. Despite his successful year, Anthony was distracted by all of the attention, and was suspended on several occasions for skipping classes. He barely registered a blip on the radars of pro scouts with his skinny frame and lack of strength; many scouts felt that he was not ready for the physical demands of the NBA. In the end, Towson Catholic fell short of the state title, although he was named Baltimore's County Player of the Year, All-Metropolitan Player of the Year and Baltimore Catholic League Player of the Year.