The cross-sectional study aimed to examine the relationships between motives for smartphone use, family satisfaction, loneliness, grade point average (GPA), and problematic smartphone use (PSU). It included 519 elementary school students aged 12-16 years (M = 13.87, SD = 1.01). The authors used the Smartphone Addiction Scale, the Smartphone Usage Motivation Scale, the Illinois Loneliness and Social Dissatisfaction Questionnaire, and the Satisfaction With Family Life Scale. For girls, the study revealed a significant indirect relationship between loneliness and GPA via social interactions. There was also a significant indirect relationship between loneliness and PSU via relaxing entertainment. For boys, there were significant indirect relationships between loneliness and PSU via escapism and between age and PSU via loneliness. The results may serve as a basis for therapeutic interventions and prevention programs against PSU.