As others have described, the interview process begins with a phone screen. Afterward, there is a brief phone interview with a recruiter. During the phone interview, there are 2-3 standard behavioral questions and a couple questions to gauge your background/experience. After that, you'll have to do a HireVue. It's awkward, but it is what is is. The HireVue has 5 questions - the first is just "Boston or Palo Alto?", and the next 4 are more in-depth behavioral questions. If they like you, you'll be invited to the home office for a "super day" where you have 4-5 hours of interviews with a handful of recruiters and hiring managers. You'll have an opportunity to meet the current ADP class and see if your personality matches what they're looking for. It's stressful, but it really isn't bad - they make it so welcoming and comfortable. They ask a whole barrage of behavioral questions and personal questions to see what you're all about. There is also a writing prompt where you're given an article or situation to respond to.
As others have mentioned, they will establish deadlines for you to hear back and then routinely miss those deadlines. It's okay, don't stress. They have thousands of applicants. Just keep emailing and following up with the recruiter.
