The purpose of this study was to analyze and discuss the results of the 2018 assessment of Korean language ability of adults, focusing on writing ability. This survey was conducted with 3,000 adult men and women aged 20 to 69. The results showed that the average writing score was 121.61 in 2018, about one point higher than in 2013. This performance is generally very poor. In the 2018 survey, the cut-off score of the 2013 study was applied, but the score of the division was newly formulated through the equalization of the survey tools, and each grade was classified into levels 4, 3, 2, and 1. In addition, except for the variables newly introduced in 2018, the change in the participants’ language ability was confirmed based on the variables set in 2013, namely sex, age, regional scale, education, and occupation. In 2018, the ratio of level 1 increased(+9.4%p), so the order of ratio of levels 2, 1, 3, and 4, compared to the ratio of levels 2, 3, 1, and 4 in writing in 2013. The overall average was similar to that of 2013 but the ratios of levels 3, 4 increased slightly, and 1 increased greatly, indicating that there was a slight variation in the writing ability of the Korean adults. When the participants were grouped by variable and ranked according to their writing skills, the scores of participants in their 20s, 30s, were higher than the scores of participants in their 40s and 50s. In terms of region size, the scores of participants in the urban areas were higher than the scores of participants in rural areas. The ranking by occupation showed that the scores of mental workers were higher than the scores of manual workers. Then, the ranking by education showed that university graduates had higher scores than high school graduates and middle school graduates. However, there was no difference between the scores of men and those of women. Based on the findings, we propose the following. First, to improve writing ability among the general public, practical educational programs should be developed. Second, social participation through writing should be encouraged at the national level and people should be encouraged to use their writing skills throughout their lifetime. Third, a large-scale writing assessment environment should be created to improve the validity, reliability, and authenticity of the evaluation. Finally, the subject variables should be closely analyzed to inform policy-making.