In this study, it was aimed to examine whether or not adolescents’ assertiveness and avoidance predicted phubbing behavior. This study was conducted with 9th, 10th, 11th, and 12th grade students in 3 different high schools in a province in Central Anatolia in the first period of 2018-2019 academic year. A total of 634 students, 430 girls and 204 boys participated in the study. The data were collected using by Phubbing Scale, The Assertiveness Scale and personal information form developed by the researcher. For data analysis, t-test was employed for binary variables, and one-way anova for multiple variables. Whether or not students' assertiveness and avoidance predicted phubbing behavior was determining by hierarchical regression analysis. The study findings revealed that gender and type of school did not have an effect on their phubbing behaviors. However, the fact that the telephone used was a smart phone was effective on phubbing behaviors. There was a negative significant relationship between assertiveness and phubbing. There was a positive significant relationship between avoidance and phubbing. In this study, it was determined that both assertiveness and avoidance were significant predictor of phubbing. The assertiveness, avoidance and the telephone used are effective in explaining the phubbing behavior.