Can I dispute a marriage settlement agreement after my husband dies?

Death of one of the parties has nothing to do with this. You cannot dispute a valid settlement agreement, i.e., one that was made voluntarily, with full knowledge, the opportunity to consult outside counsel and made with full disclosure of assets/debts. If there was something which affected one of these elements (some kind of fraud or concealing of assets) then the agreement could be challenged, but after this much time, I would think any challenge would be barred by laches/statute of limitations. Why are you suddenly now dissatisfied with the agreement? Or if there was some fraud by the deceased spouse, why is it coming out now? And its not necessarily where you lived at the time you signed the agreement. Did your ex-husband live in Pennsylvania at the time he died? Or elsewhere? If somewhere else, that state's law may govern as to any challenges brought. Did a family law attorney represent you at the time of the divorce and with regard to the marital settlement agreement? If so, then I would go back to the family law attorney who represented you and ask about why you wish to challenge this now based on whatever new information you have. If not, then you need to consult one and pay him/her to review the agreement and see if any sort of challenge could be brought. I would also see what you stand to gain by bringing a challenging and weighing it against the costs. Litigation is very expensive. What kind of probate assets did the man have? Who will benefit from the assets? These questions need answered before you decide to embark on any challenge.