Soft skills are important in several life domains, but their role in academic achievement has not been systematically investigated. This study examines how soft skills work together with self-regulated learning, motivation, and cognitive aspects in sustaining success at school. How extracurricular activities relates to these variables is examined too. A sample of 460 school students in years 5 to 12 was enrolled and examined on 6 personal soft skills (i.e. adaptability, personal initiative, perseverance, curiosity, leadership, and social awareness), cognitive abilities (i.e. reasoning, problem solving, mental rotation, working memory), motivation to learn, and self-regulated learning as predictors of their academic achievement. A measure of extracurricular activities was also included in the analysis. The results of a path model show that soft skills predicted self-regulated learning and motivation at school, and -- through the latter -- they indirectly fostered academic achievement over cognitive abilities. While cognitive abilities also predicted academic achievement and motivation, they were found unrelated to soft skills. Extracurricular activities influenced soft skills. Overall, these findings contribute to enlarging the theoretical framework on soft skills and their relationship with other variables involved in success at school.