Will a past petty theft charge affect my immigration/citizenship application

To be eligible for naturalization an applicant must demonstrate good moral character among other criteria. If found guilty, this offense will affect your citizenship eligibility, moreover it might also affect your permanent resident status, depending on the nature of the crime and subsequent conviction. For a proper advice you need to consult with a lawyer who has experience both in criminal and immigration matters.

Most states have first offender rehabilitative programs. If you are found eligible for such program, you may be able to avoid jail time and it is unlikely that your legal status will be affected. However, you will need to disclose this conviction on your citizenship application.

Immigration law is a federal law and you can hire a licensed attorney from anywhere in the country.
The responses and information are intended to be general and should not be relied upon for any specific situation. Best of Luck!