One cause of the change in young women's behavior was World War I, which ended in November 1918. The death of large numbers of young men in the war, and the Spanish flu pandemic which struck in 1918 killing between 20–40 million people, inspired in young people a feeling that life is short and could end at any moment. Therefore, young women wanted to spend their youth enjoying their life and freedom rather than staying at home and waiting for a man to marry them.

Political changes were another cause of the flapper culture. World War I reduced the grip of the class system on both sides of the Atlantic, encouraging different classes to mingle and share their sense of freedom. Women finally won the right to vote in the United States on August 26, 1920. Women wanted to be men's social equals and were faced with the difficult realization of the larger goals of feminism: individuality, full political participation, economic independence, and 'sex rights'. They wanted to have freedoms like men and go smoking and drinking. In addition, many women had more opportunities in the workplace and had even taken traditionally male jobs such as doctors, lawyers, engineers and pilots. The rise of consumerism also promoted the ideals of "fulfilment and freedom", which encouraged women to think independently about their garments, careers, social activities.

Society changed quickly after World War I. For example, customs, technology, and manufacturing all moved quickly into the 20th century after the interruption of the war. The rise of the automobile was an important factor in flapper culture, as cars meant a woman could come and go as she pleased, travel to speakeasies and other entertainment venues, and use the large vehicles of the day for heavy petting or even sex. Also, the economic boom allowed more people the time and money to play golf and tennis and to take vacations, which required clothing adapted to these activities; the flapper's slender silhouette was very suitable for movement.

The first appearance of the flapper style in the United States came from the popular 1920 Frances Marion film The Flapper, starring Olive Thomas. Thomas starred in a similar role in 1917, though it was not until The Flapper that the term was used. In her final movies, she was seen as the flapper image. Other actresses, such as Clara Bow, Louise Brooks, Colleen Moore and Joan Crawford would soon build their careers on the same image, achieving great popularity. F. Scott Fitzgerald wrote of Crawford:

Joan Crawford is doubtless the best example of the flapper, the girl you see in smart night clubs, gowned to the apex of sophistication, toying iced glasses with a remote, faintly bitter expression, dancing deliciously, laughing a great deal, with wide, hurt eyes. Young things with a talent for living.

In the United States, popular contempt for Prohibition was a factor in the rise of the flapper. With legal saloons and cabarets closed, back alley speakeasies became prolific and popular. This discrepancy between the law-abiding, religion-based temperance movement and the actual ubiquitous consumption of alcohol led to widespread disdain for authority. Flapper independence was also a response to the Gibson Girls of the 1890s. Although that pre-war look does not resemble the flapper style, their independence may have led to the flapper wisecracking tenacity 30 years later.

Writers in the United States such as F. Scott Fitzgerald and Anita Loos and illustrators such as Russell Patterson, John Held Jr., Ethel Hays and Faith Burrows popularized the flapper look and lifestyle through their works, and flappers came to be seen as attractive, reckless, and independent. Among those who criticized the flapper craze was writer-critic Dorothy Parker, who penned "Flappers: A Hate Song" to poke fun at the fad. In 1922, Secretary of Labor James J. Davis denounced the "flippancy of the cigarette smoking, cocktail-drinking flapper". A Harvard psychologist reported that flappers had "the lowest degree of intelligence" and constituted "a hopeless problem for educators".

Another writer, Lynne Frame, said in her book that a large number of scientists and health professionals have analyzed and reviewed the degree of femininity of flappers' appearance and behavior, given the "boyishness" of the flapper look and behavior. Some gynecologists gave the opinion that women were less "marriageable" if they were less "feminine", as the husband would be unhappy in his marriage. In Frame's book, she also wrote that the appearance of flappers, like the short hair and short dress, distracted attention from feminine curves to the legs and body. These attributes were not only a fashio…

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In 1922, a small-circulation magazine – The Flapper, located in Chicago – celebrated the flapper's appeal. On the opening page of its first issue, it proudly declared flappers' break with traditional values. Also, flappers defended them by contrasting themselves with earlier generations of women whom they called "clinging vines". They mocked the confining fashions and demure passivity of older women and reveled in their own freedom. They did not even acknowledge that the previous generation of female activists had made the flappers' freedom possible.

In 1923, the flapper magazine Experience included an article on police reform, possibly indicating a concern for societal issues.

In the 1920s, new magazines appealed to young German women with a sensuous image and advertisements for the appropriate clothes and accessories they would want to purchase. The glossy pages of Die Dame and Das Blatt der Hausfrau displayed the "Girl"—the flapper. She was young and fashionable, financially independent, and was an eager consumer of the latest fashions. The magazines kept her up to date on fashion, arts, sports, and modern technology such as automobiles and telephones.

Although many young women in the 1920s saw flappers as the symbol of a brighter future, some also questioned the flappers' more extreme behavior. Therefore, in 1923, the magazine began asking for true stories from its readers for a new column called "Confessions of a Flapper". Some of these were lighthearted stories of girls getting the better of those who underestimated them, but others described girls betraying their own standards of behavior in order to live up to the image of flappers. There were several examples: a newlywed confessed to having cheated on her husband, a college student described being told by a boyfriend that she was not "the marrying kind" because of the sexual liberties she had permitted him, and a minister's daughter recounted the humiliation of being caught in the lie of pretending she was older and more sophisticated than she was. Many readers thought that flappers had gone too far in their quest for adventure. One 23-year-old "ex-vamp" declared: "In my opinion, the average flappers from 15 to 19 were brainless, inconsiderate of others, and easy to get into serious trouble."

So, among the readers of The Flapper, parts of them were celebrated for flappers' spirit and appropriation of male privilege, while parts of them acknowledged the dangers of emulating flappers too faithfully, with some even confessing to violating their own codes of ethics so as to live up to all the hype.

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