As a counter-anecdote, I did a (full-day) software engineering interview in 1998 wearing an old Magic The Gathering t-shirt and jean shorts. I'm not sure what I

As a counter-anecdote, I did a (full-day) software engineering interview in 1998 wearing an old Magic The Gathering t-shirt and jean shorts. I'm not sure what I was thinking except the HR person told me they were pretty casual there-- this was for a really cool development tool company. Anyway, I went on to be hired and then promoted through dev lead, dev manager, and architect roles at that company. So, I'm not of the mind that it's something to worry too much about if you're a decent hacker. My more recent interview sessions, I've pretty much always been wearing a suit or at least business casual, but I wouldn't say it's a hard-and-fast rule, especially for a startup and junior position. Still, YMMV. If a company makes a huge deal about you not being well-dressed then they probably aren't going to be the most flexible company to work for. I know I don't tend to judge candidates specifically by the way they dress, but those who look comfortable in nice clothes do come across more professional.