Here is a sampling of some of the questions you can and cannot ask during a job interview.  A PEO can help you compile a list of "appropriate" interview questions and edit your employee applications for items that will put you at risk for a discrimination lawsuit:

What you should ask:

Age
- Whether the applicant is a minor (if position warrants such a question)

Birthplace and citizenship: 
- Is the applicant a U.S. citizen?
- Does the applicant have a legal right to work in the U.S.?

National Origin
- Does the applicant read, write or speak a foreign language? (Ask about English fluency only if it is required in order to perform the job)

Race and Gender, Military status
- Some of these questions are important for reporting purposes, but are permissible only if all applicants are asked the same question.

What you should not ask:

Age
- Age, date of birth, or any other questions that will to help disclose the age of the applicant.

Birthplace and Citizenship, National Origin, Sexual Orientation
- Most of these questions are illegal.  A PEO can give you the specifics.

Race
- Do not inquire about or make reference to the applicant’s race, color, complexion, or other physical characteristics.  You cannot require a photograph before the applicant accepts a position.

Religion
- Do not ask any questions related to religion before an applicant has been offered a position. After an applicant has been offered a position (but before he or she is hired) it is appropriate to ask questions related religion only to determine whether the employee will observe any religious days and need special accommodation such as time off from work.

Confused? It might be time to think about outsourcing your Human Resources functions to a Professional Employer Organization.

Source: London, Julie T.  “Inquiry Guidelines for Job Interviews,” EEO Update