The study aimed to reveal the relationship between self-assertion and decision-making among tenth grade students in the South Al-Batinah governorate. The sample consisted of 300 students who selected randomly. The researcher used the descriptive approach in its two styles (relational / comparative) and the data were collected using two tools: the first one is the Rathus Self-Assertion Scale (Rathus, 1978), and the decision-making scale. The results of the study showed that the level of self-assertion among the tenth grade students in the governorate of South Al Batinah was medium, and the results indicated that the level of decision-making was moderate. Moreover, the results showed that there were statistically significant differences at the significance level (α = 0.05) in the estimates of the study sample in the self-assertion scale, which is attributed to the gender variable. The differences has shown in function for the female sample. It also showed a positive relationship between the level of self-assertion and decision-making. This means that whenever the self-assertion level raised, would raise the decision-making average.