I work with young children and needed to wear something under my dresses to help keep little hands from going where they shouldn't.  These work really well because they are snug enough to not cause a lot of bulk and don't ride up horribly (they do a little).  Since I already bought them, I also use them on the weekends when riding my bike since I prefer to wear dresses when it's warm out and I don't have to worry about making sure it stays down with these underneath!