I'm sure every college is different but from a very basic admissions perspective schools probably want to hear a good reason for why you are leaving your current institution and a good reason why you are selecting their institution.  For example,  a good reason may be that after much research and deliberation you have found that their program is better suited to your interests and academic goals than the one you are currently enrolled in. Whereas an undesirable reason would be that one of your friends is transferring to that school.  Keep in mind that institutions spend a lot of time and money recruiting and processing students, so they want to make sure that you have good reasons for wanting to come and that you are likely to stay.