I have an interview coming up for what is technically only an internship position at an automotive company, and while I was told that I shouldn't feel obligated to wear a suit and tie, I'm really excited for this potential opportunity and definitely want to go in looking my best. It's just what feels right to me. It is a professional environment, after all...
But just asking, what do you guys think? Do you personally think it's ever possible to overdress for an interview?
Rule of thumb: Dress for the position one higher than the one you are interviewing for. Too much and they'll think you're unrealistic about what you're actually applying for, and too little and they'll think you aren't serious about the interview.
For an internship in a professional environment, I would definitely where I suit. I've worn a suit to all of my engineering internship interviews and have never felt overdressed. In fact, I felt a little under dressed at my automotive company interview when the guy came out in a full three piece suit. But that was an exception not a rule. In a suit, you'll probably be more dressed up than your interviewers, but your level of dress will not be distracting either as too much or "he doesn't even care" too little.
Bonus tip: avoid wearing red or overly bright colors to an interview. Red is a power color and conveys anger and aggression, not messages you want to send interviewing for an internship. Bright colors can be intense for certain work environments/company cultures. Best to stick to more conservative colors, and save the crazy stuff for after you get the job.