I'm currently on H1-B. My wife joined me on a dependent visa (H4), and got into school to do her Masters's. She then changed her visa status from H4 to F1.

She has no income. Can I claim her as a dependent when I file my next tax return? If not, what would be the best approach for filing my returns?

If you are married, then you can file joint return as residents.

If you are a resident and file a separate return, then you can claim exemption for your spouse if she had no income in 2009.

If you file nonresident return, you do not get her exemption. She must also file her return or file Form 8843 if she did not have any income.

Filing jointly is the best way to go, though when your wife begins working on CPT/OPT, she needs to make it clear to her CPT/OPT employer that she is NOT liable for FICA (Social Security and Medicare) taxes even though she is filing jointly with you.