Beginning with an online application, there was a phone screen, and then an on-site interview.
As this firm tends to recruit interns from the same local universities, the rapport was formal but not stilted. The phone screen was clearly designed to test communication skills and general background, and occurred after the standard screen on GPA/internship experience from the online application (via university website).
The on-site was all scenario questions, and aimed at soft skills, like management, your unique value proposition; the interviewer also used the interview as a review of the firm's pipeline of projects.