Question on dressing for interview?

I have an interview in the morning for a job that I really want and want to make a good impression. It is with a local Community Services Board (dealing with low cost mental health care) for an admin position. The last interview I went to-wasn't as thrilled with the job so no big loss-I wore my usual, blazer, slacks, shoes matched my bag type thing. I got in and to my amazement my interviews (agency director and another clinic worker) had on cord pants, sweaters, and clogs-I looked like I was govt official in to do an audit. I don't think it made a good impression with them. This interview is a loca branch of a larger agency which is based in Northern VA. I am torn between a sweater set and a more casual blazer-I really want to present myself well and face it, appearance counts. I don't want to overdo it but I am nervous about looking to formal. It is for a 3 day a week admin/office position that will work some with clients. Which would you go for?

And I should say the other place where I interviewed refers clients to this location for additional services. That was the first time I went to an interview and thought I should not have dressed so formally so now it's got me a bit flumexed--thanks for the answers so far. It's pretty much leaning to what I was thinking would be best.

Your best bet is if you can see how they dress before hand and dress one step more formal. If in doubt, always go more dressed up, even if it's a casual environment. It does make a good impression and is usually expected during the interview process even if it's not expected once you actually work there.
I've never known an employer to look down on someone because they came dressed more formally for the interview than expected.

i would go for the more casual blazer.
i think thats what all the other employees would be wearing being as its a admin/office job.

I would still dress UP so to speak. If the interviewer ends up being more casual, how can he/she fault you for taking the meeting seriously, and dressing for it?.....you want to come across as a professional person and clothing is one of the easiest ways to do that.

See if you can find out what the normal day to day dress is at the office. Call or if it's not to far out of the way drive over and take a peak. If it is casual, take it up a notch. A sweater set is always nice. It's casual but not overly dressy.

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