My husband is in jail and I want a divorce. What can I do?

Well, first of all, if you married your spouse while he or she was in jail, kiss using imprisonment as a grounds for divorce good bye. Kiss abandonment as a grounds goodbye. You could probably mount a cruel and inhuman treatment or constructive abandonment argument depending on the circumstances–your spouse calls and curses you on the phone, threatens to send goons to kill you, etc., or your spouse refuses to engage in conjugal visits when you go to visit him or her for your conjugal needs and this has been going on for a year….but this can get a bit thorny, I would think. You better be able to prove your allegations and hope your husband did not obtain a law degree while incarcerated.
If your husband gets incarcerated shortly after you get married (like within a year, for instance) you may want to explore annulment as a possible grounds. Did he or she conceal a material fact surrounding the circumstances of the incarceration and the marriage? Did you want kids and they assured you that they too wanted kids but then later, after incarceration, they say they don’t want kids? Does it turn out you share a close familial relationship with him or her?
If you were married before your husband is incarcerated, then you have to wait three years before you can file for a divorce on the basis of incarceration.
Now that New York has no fault divorce, I would think the above would not apply in total. You should be able to get a no fault divorce after six months even if your spouse is in jail. (Updated March 2017)