This thesis explores the consequences of grade retention, the interaction of school-starting-age rules and early ability tracking, and of a change of the ability tracking selection process. The first essay of this thesis shows that grade retention has limited educational and labor-market merits. Those that retain do not attain more tertiary education but do graduate at a later date. This delay in labor-market entry leads to a loss of earnings due to a loss of labor-market experience. The second essay shows that early differences in ability track attendance between students, created through school-starting-age requirements, do not have to be detrimental to long-term outcomes. If educational systems are flexible, students can move up, and eliminate early differences. The last essay shows that relying on teacher recommendations instead of exit test scores decreases the gap in high-track attendance between students from low- and high-income families.