How to answer employment application regarding past criminal record

You have to tell the truth;  if you get a job by lying, the company would be justified in firing you for that alone, when they found out.  Usually, they do find out, sooner or later.

Typically, though, petty theft is not a felony.  You need to look at whatever paperwork you have (if you still have it) on the arrest and conviction, or get copies from the court, which should tell you one way or another.  If you went into a diversion program for first offenders and did something like probation for a year or more, and completed that program, you may not have any record at all.

Your offense was a misdemeanor not a felony.  Therefore, if you are asked about a felony conviction you can honestly answer, "No".  If, however, you are asked about criminal convictions than you will have to answer, "Yes".

If you were given first-time offender status, after successful completion of your probation, you may not have been left with a criminal record at all.  If not, what you should do is to look into having this matter "expunged", that is cleared, from your record. There is a legal process for all of this.

I'm providing you with a link that will explain how to go about getting an expungement:  http://www.courtinfo.ca.gov/selfhelp/other/crimlawclean.htm

Best of luck.