Between Merit and Chance: Social Inequality and School Choice in Mexico City's Upper Secondary Education Admissions Reform

Abstract

In 2025, the admission system for public upper secondary education in Mexico City was reformed, intending to end the use of the standardized test used to assign students to schools and replace it with a lottery. However, because the most selective high schools decided to keep the exam, the reform resulted in a two-track system: a test for the most selective ones and a lottery for the rest. This increased the differences in applying to each segment of schools in a context already marked by institutional heterogeneity and social segmentation in access to selective schools. While the reform aimed to increase equality of opportunity in the transition to upper secondary schooling, increased institutional heterogeneity changed the conditions under which applicants choose schools, leading them towards diverging decisions depending on their socioeconomic and educational backgrounds.

Using rich administrative data and logistic regression, this thesis analyses how this reform affected the relationship between an applicant’s social origins and educational characteristics and their decision to apply to the schools that require an exam. It finds that under the new system, the share of applicants choosing exam schools decreased from 78.7% to 59.4%. This drop was associated with a strengthening of the link between applicants’ social origins and educational characteristics and their choice of exam- requirement schools, as these variables became stronger predictors in the new system. These findings highlight the difficulty of isolating the admissions reform, in its pursuit of equality of opportunity, from the broader inequalities it operates within. They also show how the design of educational systems interacts with social inequality, pointing to school heterogeneity and the dynamics that result in differences in students’ social and educational characteristics as necessary targets for increasing equality of opportunity in the transition to upper secondary schooling.

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Introduction

Filing into a school early in the morning, surrounded by thousands of other young people, to take an exam and then nervously awaiting its results for weeks had become a rite of passage for those applying to public secondary education in Mexico City. That changed in 2025, when the government announced it would stop using the test that had been used to distribute applicants among high schools since 1996. The exam, according to the government’s argument, presented itself as a fair competition, but obscured how differences in its results reflected applicants’ disparities in socioeconomic origins rather than abilities or effort. In their view, the exam legitimized social inequality, rather than neutralizing it. The test was replaced with a lottery, a change that was presented as more than a policy modification. It was described as a philosophical reorientation from meritocracy to undifferentiated access, meant to distribute the chances of admission more evenly across applicants regardless of their background, rather than consistently rewarding those who were already advantaged.

The transition to upper secondary education in Mexico City is shaped by a combination of heterogeneous schools and applicants from highly unequal socioeconomic origins (E. Rodríguez, 2015; S. A. Rodríguez, 2018; Solís, 2014). Some high schools, especially those that are a part of the National University (UNAM) or the National Polytechnic Institute (IPN), offer much better pathways to higher education and are far more selective. Under the old system, this combination resulted in the social segmentation of students among schools, as applicants from higher socioeconomic origins were more likely to access the most selective schools (Blanco, 2014; Cobos, 2023; E. Rodríguez, 2015; Solís, 2013). This segmentation was a result of applicants’ choices of schools but also of their exam results, opening the door to critiques of the exam’s effects on reproducing social inequality (Blanco, 2014; Solís, 2014).

Although the reform intended to stop the use of the exam altogether, it did not achieve its goal. After the UNAM and the IPN schools pushed to retain the exam, the result was a hybrid admissions system. It mixes a lottery track for most schools with an exam track for the UNAM and IPN high schools. Which track an applicant entered was determined by the schools they applied to. Applicants who included any UNAM or IPN school in their school selection had to prepare for and sit the exam, competing for admission based on their results. Those who applied to the other schools simply entered the lottery and waited for the draw. The reform had set out to eliminate the exam, but instead, it made opting into it a deliberate decision linked to school choice.

The existence of two tracks in the admissions system changed the conditions under which applicants decide which schools to apply to. Their school choices became even more bound up with calculations about the costs, likely outcomes and advantages of the admissions tracks, each representing a different logic of accessing opportunities: merit in the exam and chance in the lottery. Considering the strong association between applicants’ school choices and their socioeconomic and educational backgrounds, it is important to analyze if these deliberations increasingly led applicants from different social positions to apply to dissimilar schools, as part of their strategies to secure access to one of their preferred schools.

This thesis analyzes how the introduction of the new two-track admissions system altered the relationship between applicants’ social origins and educational characteristics and their school choices. It contributes to research on inequality of opportunity in the transition to upper secondary education, and to questions about how the institutional context of education interacts with social inequality to shape students’ educational trajectories. By highlighting the difficulty of isolating the admissions reform from the broader social and educational inequalities it operates within, it points to the obstacles in translating views of fairness in education into equality of opportunity. At the same time, it supports previous studies that show how the design of educational systems shapes, rather than merely reflects, the dynamics of social inequalities (Solís & Dalle, 2019).

This thesis is organized in six sections. Section 2 reviews research on educational inequality, specifically in upper secondary schooling in Mexico City. Section 3 provides an overview of education in Mexico and of the changes to Mexico City’s admission system. Section 4 describes the data sources and methodology underpinning the results and the discussion presented in Section 5. Finally, Section 6 concludes by outlining its theoretical and policy implications around social inequality in educational trajectories.

Results

Average marginal effect (AME) on the probability of choosing exam schools

Note: Reference category for school type is public general. Confidence intervals at 99%.

Predicted probability of choosing exam schools across the range of SES and Aspirations, by cohort.

Predicted probability of choosing exam schools by SES conditioned by low and high aspirations, by cohort.