The American Dream is based upon the notion that America is seen as a land of opportunity.  According to James Truslow Adams, who was the first person to use this phrase, the American dream is

"That dream of a land in which life should be better and richer and fuller for every man, with opportunity for each according to his ability or achievement."

This means that people who are coming to America from other countries are looking for a better life.  They are looking for an opportunity to use their skills and fulfill their dreams, whether that be to become a singer, actor, or attend college.  The America dream means that people will be able to make a living doing what they love for work. 

How would you define the American Dream?

I agree with most everyone above, the American Dream (at least the way I teach it when I teach The Great Gatsby in the classroom), is about the possibility of ANYONE in America being able to make himself/herself a success through lots of effort and hard work.

Notice I said the "possiblity" and not the "probability."  There are plenty of people not willing to do the hard work and put forth the effort involved to become a success.  Of course, the opposition to this idea is that some people are born into circumstances beyond their control, ... circumstances that are inescapable.  I'll leave that discussion to the social sciences section.

There is also no disclaimer that the American Dream assures happiness.  It does not.  Material success and/or a prospering business does not insure happiness.  No one is a better example of this than Jay Gatsby of The Great Gatsby.  He is a better example of the American Dream gone wrong because he not only was unable to achieve happiness in the form of his love Daisy but also he achieved nothing other than a lonely death in the end.

Let me end with this:  I disagree that The American Dream can be simplified to that of "life, liberty, and the pursuit of happiness" originating with "The Declaration of Independence," and was instead cemented and refined greatly by the makings of the great melting pot of our country:  the immigrants.  It was their thoughts and desires to work hard and pull themselves up by thier bootstraps that forged the American Dream into what it was today, ... even if they did imagine streets paved with gold.

The American Dream is an amorphous concept, defined in different ways by different people at different times in our history.  It is often defined as being better off than your parents' generation.  I believe that whether we are talking about becoming rich, buying a house or becoming influential, the American dream is about becoming whatever you want to be and not being limited by birth.

The American Dream is that ideal that you can be anything you want to be in America. In Literature it is the dream of both the wealthy and the poor. It is the idealization of the democratic ideals of America, refined by years of immigration.

I think the American Dream has also evolved into an idea the your children and grandchildren will have more than you do. You work so that they will not have to. You sacrifice, so that they will not have to. You build a life in America, so that theirs can be even better than yours.

In literature there is so much that deals with the American dream, whether it be in the "big city" or on the frontier of the nation. It in many ways is the backbone of all American literature.

The American Dream is a collective cultural narrative about the possibilities of economic prosperity. It's heavy on the consumerism, to say the least!

Martin Luther King, Jr. once said that "America is essentially a dream." The ideals of liberty, democracy and prosperity are goals to move toward, not realities to take for granted. The American Dreams tells us what we should be fighting for. No society completely lives up to its image of itself. I think the American Dreams serves us best when it makes us vigilant in the protection of our freedoms and eager to inch our way closer to a practice of democratic ideals and economic opportunity for all.

I think that another very important work to explore the American Dream is Of Mice and Men.

The American Dream is based on the idea that all Americans have an opportunity to become prosperous and independent.  Americans believe that they have the ability to work hard enough to become well-off and to no longer need to depend on other people (charity, the government, even employers).

In Of Mice and Men, we see George and Lennie pursuing this dream.  They are trying to get to the point where they can live a good life on their farm -- a life where they will not be poor and will not have to obey the commands of a boss.  This is the American Dream.

The American Dream is an important concept in many works of literature, especially when its shortcomings come to mind. Just two great works that are known for their investigation of the American Dream are The Great Gatsby and  Death of a Salesman. Putting it simply, the American Dream can be linked with the hopes and expectations of the first European settlers of the United States who regarded the new colony as a kind of Promised Land, a return to a Biblical Garden of Eden, where anything was possible and you could reinvent yourself, making yourself a success through lots of hard work and effort. Clearly, whilst there is a certain amount of truth in this concept, many critics argue that it naively ignores the way that other forces shape and impact our lives. Such works as Death of a Salesman have been analysed by Marxist critics who argue that this text shows how really the American Dream is a misleading and dangerous illusion that damages people by dangling tantalising yet unnattainable dreams in front of them because they are very small cogs in a very big economic machine.