This paper estimates the effects of extending the school day during elementary school on students’ educational outcomes later in life. The analysis takes place in the context of a large-scale program introduced in 2007 that extended the school day from 4.5 to 8 h in Mexico City’s metropolitan area. The identification strategy leverages cohort-by-cohort variation in full-time enrollment in elementary schools. The results indicate that full-time elementary schools have positive and long-lasting effects on students’ performance, increasing high-stakes high school admission test scores by 4.8 percent of a standard deviation. The effects are larger for females than for males. The difference in the effects between males and females of 2.1 percent of a standard deviation represents 16% of the gender gap in the high school admission exam. Moreover, full-time schooling decreases the probability of delays in schooling completion.

本文评估了小学期间延长上课时间对学生以后教育成果的影响。该分析是在 2007 年推出的一项大规模计划的背景下进行的，该计划将墨西哥城大都市区的上课时间从 4.5 小时延长至 8 小时。该识别策略利用了小学全日制入学中各队列的差异。结果表明，全日制小学对学生的表现具有积极而持久的影响，使高风险高中入学考试成绩提高了 4.8% 的标准差。对女性的影响比对男性的影响更大。男性和女性之间 2.1% 标准差的影响差异代表了高中入学考试中性别差距的 16%。而且，