The interview process has changed since I was hired. I used a 3rd party recruiter, but now an in-house recruiter serves as the initial point of contact for interviews. She does a phone interview and those chosen to move forward usually meet later with 1-3 partners/managers and then have lunch or get coffee with some staff members at their level. Prospective administrative staff are interviewed by the direct manager and then meet with a group of partners as well as a group of managers either from the department they're applying to (if applicable) or from the firm in general (if for a non-department specific position). Offer letters are usually given quickly and applicants typically have around a week to make their decision.