Research suggests that behavioral self-regulation skills are critical for early school success, but few studies have explored such links among young children in Europe. This study examined the contribution of early self-regulation to academic achievement gains among children in France, Germany, and Iceland. Gender differences in behavioral self-regulation skills were also explored. A total of 260 children were followed longitudinally over one to two years (average age at Wave 1 was 74.5 months). Behavioral self-regulation was assessed using a structured direct observation (Head-Toes-Knees-Shoulders task) and assessment. Multilevel analyses revealed that higher levels on both ratings of self-regulation predicted higher academic skills after controlling for gender, age, maternal education, and previous achievement, but the relations depended on the cultural context. Teacher ratings were more consistently related to achievement gains than directly assessed behavioral self-regulation. Girls outperformed boys only in Iceland. We discuss universal and culture-specific findings and implications for educational practices.