Does she flirt in front of her husband? If he just laughs at her or is a flirt himself, it is a safe to conclude this behavior is considered harmless fun in their marriage. (If she turns it up a notch and is more aggressive when he's not around, you can be almost positive she is flirting with you.)

Watch closely to see if she is acting the same way with everyone else, as it could just be the way that she interacts with people in general. Be warned though that she may be the type to have a few boys on the side at one time.

Listen carefully when she's talking to see if she says things like "don't tell him, I don't want to make him jealous" or "please don't tell your wife/girlfriend." Asking in any way for you to be deceptive is a sure way to tell if a married woman is flirting with you.

Make note of the times that she calls or texts you outside of normal occurrences, such as notifying you of a party or something to do with business. If she contacts you frequently to just say hello or says something like "So did you miss me today?" she has stepped over the line.

Don't question if you have led her on and do not try to get to the root of the issue; just take comfort in the fact that you can pick up on a married woman is flirting with you before it's too late and you find yourself on the slippery slopes that lead to an affair.