My grandfather was a US citizen, do I have a right to become a US citizen?

If one of your parents became a US citizen and you lived with that parent before you became an adult at the time you parent had already become a US citizen you may already be a US citizen. Otherwise, you must apply for citizenship on your own.

Questions like this are amongst the more complicated issues an immigration attorney must address. The authority that a US citizen hasto pass US citizenship to a child born outside of the US depends on a number of factors. Generally, the most important of these factors is the length of the US citizen's residence in the US and the citizen's age during that period of residence. My advice would be to consult with a knowledgeable and competent attorney and to make sure that you fully understand that advice offered BEFORE making any decision to retain anyone's services. As i indicated above, this is complicated and if you trust the wrong person, you risk losing time and money. Find someone to help, nut make sure that you choose wisely.

It is possible that you may be a U.S. Citizen, however you case would need to be carefully evaluated. It will depend on your grandfather's presence in the U.S., the date of birth of your father, the length of time your father lived in the U.S. or why/how he lost his citizenship. I would suggest you meet with a competent immigration lawyer to discuss further.