I am a 24 year old female who is interested in taking ballet lessons. I am relatively athletic and trim, so I feel that it would be physically possible for me to handle lessons. I know that most ballet schools are designed for little girls, or pre-professional dancers. I live in Chicago, and we have some wonderful schools, but I am sure that most of them that offer classes for women my age are for experienced dancers. Dont be afraid to look in the yellow pages and call several studios and ask specific questions about their adult dance program.
Most schools do have some adult classes.
Specify that you need beginning adult classes. Its a good idea to visit the studio and look around. Get a general feel for the place and see if its somewhere you will be comfortable dancing. Ask if the have a ballet floor barre class. That is a wonderful way for adults to enter the dance world without too much physical strain initally.