Research online. The Party School Network and The Princeton Review each release yearly lists of top party colleges based on their criteria. These lists usually provide a breakdown of other ratings for that particular school.
Visit your local library or bookstore. The Princeton Review publishes a complete guide yearly on colleges in numerous categories, including top party schools.
Ask around. Friends and family provide first-hand accounts of party life at their respective college. Contact colleges and alumni organizations for more information about the social scene of a given school.