The main purpose of this study is to examine the possible relationships between academic locus of control, positive thinking skills and grit in high school students. The participants of the research are composed of 288 adolescents continuing their high school education from 4 different schools in Agri, Turkey, which were selected with convenient sampling. 168 of the participants are male and 120 are female students. Pearson's moment correlation analysis was used for determining relations among variables, and multiple regression analysis was used to determine the regression coefficient of the variables on each other. Parametric tests were used, because the data showed a normal distribution. p <0.01 significance level criteria were taken. According to the findings, positive correlation between internal academic locus of control and positive thinking skills was found (r = 0.54). A positive correlation was found between the internal academic locus of control and grit at (r = 0.58). A positive correlation was found between positive thinking skills and grit (r = 0.61). The internal academic locus of control, external academic locus of control and positive thinking skills explain the 50% of the grit's total variance. Based on this evidence, it can be said that the academic locus of control and positive thinking skills are important predictors for grit.