This is what I found from internet:
http://www.huffingtonpost.com/kat-cohen/the-truth-about-needaware_b_2758566.html
ZT:
How does this admissions policy work?
When determining financial aid packages for students, schools try to meet full need. This doesn't necessarily mean they're providing full scholarships to everyone admitted. Many times "meeting need" means a combination of scholarships, grants, and loans, with the latter being the most controversial.
Schools with large endowments are usually able to meet the need between what a family is expected to contribute and a financial aid package. But the promise of "need-blind" consideration can be sticky, with some schools not able to meet every student's full financial need. This is called gapping.
To make things more complicated, there are varying types of need-blind policies. Schools can either be need-blind and meet full need of all applicants, need-blind but only meet some need, or need-blind and meet full need for only U.S. applicants, which means the ability to pay will be considered for international students.
Most public colleges and universities are need-blind and can meet varying amounts of financial aid. However, there are few private colleges that are truly need-blind, leaving many students to wonder where they will fall in the admissions pile if they need a significant financial aid package.