My father, who is now deceased, was a dual german & american citizen. He was born in germany to my grandmother who is German and my grandfather who is American. My grandparents relocated to the states 5 years after my dad was born. My grandparents kept my dads german birth certificate & german passport. Upon relocating, my grandmother gave up her german citizenship (during the 50's dual citizenship was not recognized). Years later, I was born. I was born in the states. Four months after I was born, my parents married. My question is-- Am I entitled to dual german/american citizenship since my father was a german (and american) citizen at the time of my birth? Can I still claim this even though my parents were married shortly after my birth? And, can I still claim this even though my dad is deceased and never registered my birth with the German government since I was born in the states?

The question would be if your father was still a German citizen. Since your grandma gave up German citizenship upon immigration to the US, it could that the same happened with your father, however, rules for children are often different. Your best bet would be to contact the German embassy.

Dual Nationality | United States Diplomatic Mission (http://germany.usembassy.gov/acs/dual_nationality/)

The question would be if your father was still a German citizen. Since your grandma gave up German citizenship upon immigration to the US, it could that the same happened with your father, however, rules for children are often different. Your best bet would be to contact the German embassy.

Dual Nationality | United States Diplomatic Mission (http://germany.usembassy.gov/acs/dual_nationality/)

Thank you for your reply. I know for a fact that my father never renounced his German citizenship. I'm just not sure that because my grandmother did so, did that have any effect on my father's - as he was a minor?.

You don't really have to renounce it, the moment you take a different citizenship, the German one is revoked if you didn't get permission beforehand (Im German too with double citizenship). The case might be different for minors, so ask the German embassy, they can help you.