King Sejong's idea of making common people who had no opportunity of studying Chinese characters literate was very exceptional and reformative in the social atmosphere at that time, and it took a long time for the idea to be realized. First of all, the governing classes still maintained official literary lives using Chinese characters, and there was very slim chance for Hangeul to infiltrate through them. Instead, Hangeul slowly began to expand its influence by playing a role different from Chinese characters. As Hangeul was invented for common people, it played an important role among people at first. Although people who are capable of using Hangeul kept increasing among the governing classes, they rarely used Hangeul unless in an exceptional cases because they were using an official, privileged characters, Chinese characters and Chinese writings.

On the other hand, since common people had no choice, they gradually started to use Hangeul. The Hangeul message of King Sunjo shown above implies that Hangeul was widely spread among common people at that time. There was an event that shows not only common people but also more and more noble class people could read and write Hangeul. When a document written in Hangeul that criticizes the tyranny of Yeonsan-gun appeared in 1504, Yeonsan-gun gave an order to ban learning Hangeul, to burn all the books in Hangeul and to report all the people who could use Hangeul.

It seems that the person who wrote the document was a noble man, and he intentionally used Hangeul in order to avoid exposure of his identity.
Women played an immense role in expansion of Hangeul use. Although many women were taught Chinese writings in noble classes, it seems that they gradually used Hangeul much. Therefore, they use Hangeul when exchanging letters with other women or with men. Also, many books mostly for women were published in Hangeul. This shows the important role of women in the expansion of Hangeul use as well.
Secondly, the role of Buddhism can't be ignored. Although Joseon Dynasty formally took the policy of respecting Confucianism and repressing Buddhism, Buddhism still kept an important position in common people's mind. Especially, the royal people who led invention and use of Hangeul like King Sejong and Sejo had strong belief in Buddhism.

Therefore, among many projects that can be done using Hangeul, they were enthusiastic in promoting translation and publication of Buddhist scriptures. Although the vassals made strong protests against their attempts to build Buddhist temple in the palace in a bid to hold worship in front of Buddha and publish Buddhist scriptures, these projects continually lasted throughout the time of King Sejong, Moonjong, and Sejo. Many Buddhist temples throughout the country went on publishing Buddhist scriptures afterward. Its purpose was to let common people realize the truth of Buddhism and die achieve their religious goals by reading Buddhist scriptures written in Hangeul.
In 17th and 18th century, novels contributed much in diffusion of Hangeul. Many people in the governing class were indulged in Chinese novels at that time. They read not the pure old literatures but love stories and popular novels and some noble people who read much of them used similar literary styles in their own writings as well. (This also gave an excuse to King Chungjo of enthronement()) These novels were translated in Hangeul and widely read by common people, too. Hangeul novels were distributed in the form of transcription at first, but later they were published in imprinted forms(commercial publication) due to their commercial values.

These fashion of novels and rise of commercial publications were a sign of progress toward the modern times. Also, switching over from the medieval culture of emphasizing common literary language to the modern culture that values national language is entangled with it here. The positioning of Hangeul as a dominant character of Korea instead of Chinese character meant a progress towards the modern age.

Hangeul began to be used in official documents of the country by the Reform in the year of Gabo Reform(), and the assertion that Korea could grow to a modern and strong country only if we used Hangeul instead of Chinese character became powerful. Even though it took a long time, the idea that King Sejong had in mind when he invented Hangeul eventually came true.