I got a call from ZS through an employee referral. I was asked to come and take AMCAT exam at their office. First Round: AMCAT - Online Exam A ~80 minutes online exam to test your quantitative and verbal ability, data interpretation, and something related to pattern matching. A few minutes after the exam itself, they told me that I cleared the exam. Each of the following rounds are elimination round. Second Round: Case Round. A business case is given to you. It has all the details, tables, and graphs regarding the case and you need to use that information to answer six questions (two questions each in three different parts of the same case) in 25-30 minutes. After attempting the case study on paper, you discuss how you went through the case with a consultant. This takes another 25-30 minutes. Maybe more. As already mentioned in the other experiences here, they are not looking for the right answer. They want to see if you are capable of having a thinking process, and are not just saying whatever comes to your mind first. The case, in itself, is not hard but the lack of time to solve it makes it so. Third Round: Behavioral Round You will have this round with another consultant. Most of the times, you are asked few guesstimates and puzzles. Your resume is also discussed here. If you have work experience, you'll asked (at times, in detail) about your projects. Consultant, in this round, also ask you behavioral questions and some general questions based on your experience. This round can vary from 40 mins to an hour. Fourth Round: Principal Round If you have reached this round, you can be really assured that you will be selected. Not completely assured, but very assured. This interview is with a principal at ZS Associates. It is more or less like the previous behavioral round, where the principal is trying ascertain whether you are good fit to the company or not. Overall, it was a very good interviewing experience. During the interview process, they arrange cab facility (if you're from somewhere local) or flight and accommodation (if you're from outside). Even in the office, they make you feel comfortable. The interview process, as a whole, might seem difficult. My advice would be to concentrate on one round at a time. Be polite in your conduct and honest in your answers.