I was born in the United States in 1980 to a British father and American mother. My father still lives in the US and has a green card. At the time of my birth, no attempt was made to get me a passport or dual citizenship. Am I still able to get a UK passport? If so, what is the procedure?
As you were born before 1983 and your father was a British Citizen, section 5 of the 1948 nationality act applies to you. Based on this act you are considered a British Citizen by descent, if your father is a British Citizen otherwise than by descent, for example he was actually born in the UK or became citizen by naturalization or registration.
If these apply, then you are already a British Citizen by descent, which means that while you are considered a citizen, you will not automatically pass this citizenship on to your children.
Note, that if your father was already a British Citizen by descent (e.g. he was not born in the UK, but got the citizenship through his parents), then probably you are not a British Citizen, and cannot apply for a UK passport.
If you are outside of the UK you need to apply online. If you are inside the UK (for example you entered the country with your US passport), then you can apply by post.
In either case you will need all of the following documents to prove that you are a citizen:
(you will also need to supply some other things, like two passport photographs and your current, non-UK passport as well)
If you do not have all of the documents necessary to complete the application then you have to write to the Home Office asking them to confirm that you are in fact a British Citizen (by descent). For this you should fill out the Confirmation of British nationality status form (also called Form NS). You have to sent the filled out form to this address: