This study investigates the impact of an extended school week in 30 primary schools on track recommendations, an achievement-related outcome, at the school level. The intervention is part of a major urban policy in one of the most disadvantaged areas in the Netherlands. Register data are used to examine changes in track recommendations between 2010 and 2020. Control schools are selected through genetic matching based on educational and demographic variables, after which comparative interrupted time series estimate the causal effect. The findings show that, on average, track recommendations in the intervention schools did not structurally increase compared to the control schools. We critically discuss how these results might relate to implementation barriers such as the partial top-down design, program quality and coordination, and teacher shortages. We contribute to the literature by showing how difficulties with program implementation are likely to produce null findings.