With all the competition to get into the right universities to secure the best jobs, secondary school students are often encouraged to take after-school classes in subjects already taught in school to help them improve their performance--even if that means forsaking other fun and interesting ways of spending after-school hours, such as playing sports, taking music lessons or volunteering at a local community centre or hospital. Students in the Organisation for Economic Cooperation and Development (OECD) area spend an average of nearly two-and-a-half hours per week in after-school lessons. In Greece, Israel, Korea, Turkey and the partner countries Azerbaijan, Kyrgyzstan, Qatar and Tunisia, students spend over four-and-a-half hours per week in such classes. Does that investment in after-school classes pay off? Not necessarily. In fact, according to findings based on PISA (Programme for International Student Assessment) 2006 results, learning time spent in after-school lessons and individual study is negatively related to performance. This issue of "PISA in Focus" discusses whether investing in after-school classes pay off.