How long after an interview should you hear something back?

_Kaiser_

Like others have said, I'd be inclined to not put my eggs in one basket and keep looking - you may find/get something even better.

As someone who has interviewed and expanded my team though I can tell you that if it's a big company there'll often be layers of approvals to go through before someone is taken on.

While I know from first-hand experience (as both potential employee, and the guy who wants the spot filled) how frustrating that is, it's not malicious by any means. Often decision makers will be hard to reach due to meetings, may be travelling, or on holiday. The Finance team may want internal justifications before they approve and so on.

By all means follow-up, but try and be patient as well - but keep your eye out in the meantime.

Zeek12

I'd second the thoughts outlined already; you should definitely continue your jobsearch. No sense in banking everything on this one to come through.

But you should'nt give up on it completely either. I've had a delay of almost two weeks between 1st interview and the call for the 2nd interview in the past.
If its a large organization (with many "sign-offs" required on the candidates for the next round), it can take some time. It's also possible you were one of the first candidates interviewed - in which case there could well be a bit of a time-gap until the call for 2nd interview goes out.