at what age do you consider someone an adult in your OPINION?

I need to answer your question as written, and that answer would be 18. To make excuses for someone older is just not right! To expect more from someone younger isn't reasonable either.

I understand that people often "get more sense" as they get older, but technically we should expect them to be doing their job, or holding up their end of bargains, or responsible for their mistakes at 18.

Edit: This IS an important question, and I'm going to rant on. Men are considered worthy of fighting in the front lines in battle at 18. Millions upon millions have died for their country in the past century at that age. Women are considered old enough to leave their families, have babies with a husband or on their own; and that is considered their right. They are also old enough to legally determine they want to end the pregnancy without anyone else interferring. I'd say that we HAVE to consider these people mature adults....perhaps STUPID mature adults, but none the less deserving of being considered adults.

What frosts me are situations like dear ol' Monica, who was 22, had White House clearance, but when they talked about her and her affair with Bill, she was a poor young girl, so naive, and not knowing anything. (I'm NOT excusing Bill, but speaking of Monica). But when some male total nut-case at 17 or 18 goes and acts out a murder, or most any other crime, HE is an adult to be tried as such, and considered as such. But yet the 18 year old girl, must be considered a full adult when applying for a job, etc. Somehow this double standard seems just a bit foolish sometimes. Rant over: 18 is adult.

If an eighteen year-old acts like an adult, I will call him or her an adult and treat him or her like such. Same goes for a sixteen year-old.

As far as development goes, I don't think it's realistic to pinpoint a time when we're "adult" or "fully mature." Most of us constantly learn new things and develop as people throughout our lives.

Christ and Buddha were spiritually enlightened in their mid-30's

There is sexual maturity(age 13), physical maturity(age 21), spiritual maturity(age 34), physical decline (age 55).

All of these follow the Fibbonaci Series of numbers

http://en.wikipedia.org/wiki/Fibbonaci_Series

Also, there is the theory that people enter a new phase of maturity every 7 years. This coincides with the Fibbonaci sequence at ages 21 and 35(almost) and 56(almost).

IMO, there is no one age at which everyone is mature enough to be considered to be an adult.

IMO, when one is able to assume full responsibility for themselves and their actions--physically, financially, legally and morally--they are an adult.

I think it has to do with maturity, not age. I've met 26yos who are still children, and 5yos who are more adult than most people.

At whatever age they start acting like one.