The aim of this study was to examine whether personality traits, motivational strategies of self-regulated learning, the average daily duration of mobile phone use and the percentage of mobile phone use during studying predict expected final grades in subjects taken at the Croatian State Matura (Croatian language, mathematics and foreign language) among high school students. The study included 254 students from the 1st, 2nd, and 3rd grades of two high schools in Zagreb (62.6% female) who completed an online questionnaire during class. The Mini-IPIP personality traits questionnaire (Donnellan et al., 2006), the Motivational Strategies Scale (Lončarić, 2014), data from mobile devices on the daily average use of mobile phones and the estimation of the percentage of mobile phone use during studying were utilized. It was found that students spend on average more than 5 hours per day using their mobile phones. The proposed hypotheses were only partially confirmed. Neuroticism and goal setting were found to be statistically significant predictors of the final grade in mathematics. Gender and goal setting were statistically significant predictors of the grade in the Croatian language, while grade level, extraversion, and agreeableness were significant predictors of the grade in the first foreign language. The average daily duration of mobile phone use and the percentage of mobile phone use during studying were not statistically significant predictors for any of the criteria. Possible explanations for these results include the way these variables were measured, as well as the possibility that high school students efficiently use the remaining time not spent on mobile phones, which does not affect their academic achievement.