I first had a phone interview with HR. She asked me general questions about things I listed on my resume, like what did I do in my current work and what am I doing in school and what are my goals? She called me the next day to tell me that the hiring manager was interested in interviewing me. The interview was a panel of 3 people. Ameren uses the "behavioral interview" approach. This format aims to getting to know more about your behaviors in specific work situations from the past. These questions often start with "Describe a time when..." or "Give me an example of a time when you had to do X, and what was the outcome... what could have done better" I got a call the next day with an offer to the Co-Op position, which I took.