Target uses a situation based interview process (ie: Tell me about a time when...). This type of interview allows them to:
1. See how good you are at thinking on your feet.
2. Assess your problem thinking skills.
3. Compare candidates apples-to-apples.
They are looking for a specific answer format:
1. Describe the situation
2. What steps did you take?
3. What was the outcome?
Always try to end the story on a positive note (ie: How you were able to fix/resolve the situation or prevent future problems from happening)
The best way to prepare for this type of interview is have 4-6 good work stories, that are fairly easy to explain (you don't want to get stuck trying to explain a convoluted story), that reflect different leadership skills. This way when you are asked a situation based question, you will already have a set of scenarios in your head that you can plug into the different interview questions.