Objectives: Numerous studies have examined determinants contributing to methylphenidate adherence and persistence, but these were mainly conducted in adults. These determinants are likely to be different in children as they usually rely on their parents to provide them with the care they need. The objective was to study child and family characteristics as determinants of methylphenidate adherence and persistence in children. Methods: The study population consists of 307 children from the Generation R Study in the Netherlands, who had at least one dispensing record of methylphenidate until the age of 16 years. Adherence was defined as a medication possession ratio ≥0.80 up to 2 years after treatment initiation. Persistence was defined as the duration of treatment until a discontinuation period of ≥6 months. Family and child characteristics were tested as determinants of adherence with multivariable logistic regression analysis. Persistence was evaluated using a Kaplan-Meier analysis. Results: Children of mothers with one child (adjusted odds ratio [OR]: 2.31, 95% confidence interval [CI]: 1.17-4.54) or of mothers with an average household income (compared to high) were more likely to be adherent (adjusted OR: 3.45, 95% CI: 1.43-8.31). Children who started treatment at the age of 12-16 years (compared to <12 years) (adjusted hazard ratio [HR]: 3.55, 95% CI: 2.54-4.98) and girls (adjusted HR: 1.44, 95% CI: 1.07-1.95) were more often nonpersistent. Conclusion: Both child and family characteristics may play a role in methylphenidate treatment adherence. Furthermore, gender and the start age of treatment were found to be associated with nonpersistence. These findings may be important for health care professionals when initiating methylphenidate treatment in children.