The main purpose of this study was to examine whether or not assertiveness predicted adjustment to university by determining university students' adjustment levels to university. The study was conducted with first-year students who were attending a university in Central Anatolia in 2018. A total of 438 students, 322 females and 116 males, participated in the study. The data were collected using the University Life Scale, the Assertiveness Scale and the Personal Information Form developed by the researcher. For data analysis, t-test was employed for binary variables, and one-way ANOVA was employed for multiple variables. Whether or not students' assertiveness predicted adjustment to university was determined by regression analysis. The study findings revealed that students' sex, high school they graduated from, the number of their siblings, their source of income, social activity they engaged in prior to university and their accommodations did not have effect on their adjustment to university. However, choosing their major willingly, perceiving their income as sufficient, the city they lived in and perception of their economic situation had effects on their adjustment to university. Furthermore, the study determined that the university students' assertiveness total scores predicted their adjustment to university, emotional adjustment, personal adjustment, adjustment to the opposite sex, social adjustment, academic adjustment and total adjustment scores.