The Millionaire Next Door: The Surprising Secrets of America's Wealthy () is a 1996 book by Thomas J. Stanley and William D. Danko. The book is a compilation of research done by the two authors in the profiles of American millionaires.

The authors compare the behavior of those they call "UAWs" (Under Accumulators of Wealth) and those who are "PAWs" (Prodigious Accumulators of Wealth). They found that millionaires are disproportionately clustered in middle-class and blue-collar neighborhoods and not in more affluent or white-collar communities. This came as a surprise to the authors, who anticipated the contrary. Stanley and Danko's book explains that high-income white-collar professionals are more likely to devote their income to luxury goods or status items, thus neglecting savings and investments.

UAWs versus PAWs Under Accumulator of Wealth (UAW) is a name coined by the authors and used to represent individuals who have a low net worth relative to their income. The authors offer a rule of thumb (more appropriate for those who are older and thus have been earning longer): “Multiply your age times your realized pre-tax annual household income from all sources except inheritances. Divide by ten. This, less any inherited wealth is what your net worth should be.” Take a 50-year-old doctor earning $250,000. According to the rule of thumb, he should be saving 10% yearly and should have about $1.25 million in net worth. Those whose net worth is lower can be considered "Under Accumulators". UAWs focus on consuming income, rather than saving.

A Prodigious Accumulator of Wealth (PAW) is one who accumulates well over one tenth of the product of their age and their realized pretax income.

Most of the millionaire households the authors researched did not have the extravagant lifestyles that most people would assume. This finding is backed up by surveys indicating how little these millionaire households spent on such things as cars, watches, clothing, and other luxury products or services. Most importantly, the book gives a list of reasons for why these people managed to accumulate so much wealth (the top one being that "They live below their means"). The authors make a distinction between the 'Balance Sheet Affluent' (those with actual wealth, or high-net-worth) and the 'Income Affluent' (those with a high income, but little actual wealth, or low net-worth).

Main points The authors talked about the seven most common traits that showed up among those that have accumulated wealth. Those common traits are: 1. They live below their means; 2. They allocate time and money efficiently; 3. They value financial independence over displaying high social status; 4. They did not receive regular cash support from their parents. 5. Their adult children are economically self-sufficient; 6. They are good at targeting market opportunities; 7. They chose the right occupation.

To increase net worth, spend less than you earn Anyone who spends what they earn or more than they earn will fail to increase their net worth.

Avoid buying status objects or leading a status lifestyle Buying or leasing brand-new, expensive imported vehicles is poor value. Buying status objects such as branded consumer goods is a never-ending cycle of depreciating assets. Even when you get a good deal on premium items, if you replace them frequently, the older items hold no value and have become a sunk cost. Living in a status neighborhood is not only poor value, but you will feel the need to keep buying status objects to keep up with your neighbors, who are mostly UAWs. The authors make the point that hyper-consumers must realize more income to afford luxury items and become more vulnerable to inflation and income tax.

PAWs are willing to take financial risk if it is worth the reward PAWs are not misers who put every penny under their mattress. They invest their money for good returns, and will consider riskier investments if they are worth the reward. Many put money not only in the stock market, but also in private businesses and venture capital.

Family and Generational Wealth The authors observe that UAWs tend to have children who require an influx of their parents' money to afford the lifestyle that they expect for themselves. Their parents are less likely to have taught them about money, budgeting or investing.

Spending tomorrow's cash today The most prominent idea shared by UAWs and American society in general is "spending tomorrow's cash today".Stanley, Thomas, and William Danko. The Millionaire Next Door. New York: Pocket Books, 1996. This is the leading cause of debt and a lack of net worth in the UAW category. This contradicts the common belief of a PAW: "save today's cash for tomorrow". Many UAWs do plan, under certain conditions (such as a rise in income), to use investment strategies to accumulate wealth; however, most do not actually use investment strategies to accumulate wealth once the initial conditions are met. For example, Under Accumulators of Wealth will promise to start investing once they have earned ten percent more in annual income. Unfortunately, when most receive that extra ten percent of income, there isn't an investment made. These claims and ideas usually branch off an initial belief that a lack of wealth can simply be solved by an increase in income. Even among those that do invest money, most invest only because they have an excess of income. Between 2001 and 2004, the median family income dropped 2.3% and in response, the percentage of families who owned investment stocks fell by 3.3%, showing that investments are only made in times of excess.

"Better Than" theory The "Better Than" theory is one of the main reasons many UAWs don't hold true to their promise to invest after a rise in income. The theory is that the UAW's "necessity" for that income will also rise in response to the risen income level. According to a study conducted by Yale and stated in The Millionaire Next Door, individuals measure the level of their success through comparison to nearest neighbors and closest relatives. Therefore, as the level of income rises, so will their desire to outperform those that they compare themselves to.

"Better Off" theory In addition to the "Better Than" theory, there is a "Better Off" theory. This theory suggests that those UAWs who grow up in a poor family and land a high-income career have a tendency to feel the need to be "better off" than their parents. To a UAW, "better off" implies a larger house, a respectable degree, a foreign luxury car, a boat, and a club membership. A hypothetical example is provided in The Millionaire Next Door to explain this concept. Teddy Friend is a typical UAW that grew up in a poor family but was still exposed to a rich lifestyle at school. He saw "rich kids" and decided that one day he would be "better off" than his poor parents. Sure enough, when Mr. Friend reached a high income level, he indulged himself in possessions. He bought a large home along with a foreign luxury car. According to most UAWs, he lives a very comfortable lifestyle. He lives a very comfortable lifestyle in terms of possessions, but in terms of financial security, Mr. Friend's lifestyle is uncomfortable.

Money: a renewable resource Another belief that UAWs have is that "money is the most easily renewable resource". This belief usually is another leading cause for UAW's consumption and investment habits. Money is more easily spent now than it is saved. In America it is easier to generate a high income than it is to accumulate wealth.

Spending habits When it comes to spending habits, UAWs are everything but frugal. A typical UAW tends to live in luxury, style and comfort. Not all UAWs fit these characteristics. A $50,000-a-year janitor can be more of a PAW than a $700,000-a-year doctor. The spending habits that UAWs have are a direct effect of the “Better Than” theory.

Million dollar choices Some of the financial choices that UAWs make are considered to be “million dollar choices” because if the choice hadn't been made, the UAW would have in excess of a million dollars. An example given in The Millionaire Next Door explains how small purchases of cigarettes over a long period of time can represent a large sum of money. Mr. Friend's poor parents smoked at least three packs of cigarettes a day. Three packs a day over 46 years translated into a sum of money that exceeded the value of their home by $33,000. Had the Friends invested and reinvested that money over a 46-year period, the portfolio would have exceeded $2 million. The point is made that a UAW makes choices that have a substantial effect over the long term, while having a marginal effect in the immediate future.

Car shopping habits According to the authors, a common UAW drives a current model car, purchased new, and may have financed it on credit. PAWs rarely purchase new model cars and are less likely to own foreign or luxury vehicles. An example from the book details a UAW that spent roughly 60 hours researching, negotiating and purchasing a new car. In the end, while the car was purchased "near dealer cost," the UAW's time and money could have been more efficiently spent creating wealth rather than collecting possessions notorious for depreciating in value. The authors contrast the story with a PAW who decided that the pride of owning a brand new car wasn't worth the $20,000 price difference.

Investing strategies Most UAWs believe in the "Better Off" theory, "Better Than" theory, or both – so they value other people knowing (or at least believing) they are wealthy right now more than maintaining and growing their wealth over the long term. Most PAWs minimize their realized income and / or taxable income, they maximize their unrealized and / or nontaxable income, or both. The strategy helps them grow wealth over the long term.

Here is one example. Buying a car (whether new or used) cannot be deducted from your taxes, but putting money into a retirement savings account can. On average, it seems that UAWs spend much more time than PAWs figuring out which car to buy. Meanwhile, UAWs are less likely than PAWs to have any retirement savings, they spend less time figuring out which tax advantaged retirement savings account to use (such as a 401(k) versus Individual Retirement Account (IRA)), and they put less money in.