Crystal took her first dancing classes (tap) when she was three years old. This led to the beginning of her professional career, which started commercials at age 7. About the time she was 12 years old, Crystal stopped interviewing and auditioning for commercials; explaining that "they're like huge crowded cattle calls...". At age 11 she had her first acting role on television in a movie costarring Patty Duke. Later, at age 12 and beyond, she went on to make occasional appearances on The Wonder Years, a show in which her older sister Danica co-starred. At the age of 14, Crystal McKellar appeared in her second made-for-TV movie.