Over the past 15 years, the corequisite model of remedial education has swept through America’s community colleges. Rather than requiring academically underprepared students to complete a sequence of non-credit-bearing prerequisite courses before enrolling in college-level classes, corequisite models place students directly into college-level coursework while providing supplemental support. By 2023, more than 77% of community colleges were offering corequisite instruction.
The switch has been widely celebrated. Studies comparing corequisite remediation to the older prerequisite model have consistently found large positive effects on first-year completion of gateway courses, the introductory math and English courses required for graduation. Advocates have declared that there is “no room for doubt” about the model’s effectiveness.
But is the confidence warranted? A closer look suggests that the seeming consensus is undercut by two major factors. First, most existing research compares corequisite remediation with the prerequisite model, and the prerequisite model is known to have large negative effects on student outcomes. The improved student outcomes attributed to corequisites may largely reflect the removal of a harmful policy rather than the value added by corequisite support.
Second, in math, corequisite reforms have often been accompanied by math pathway reforms that allow students to take quantitative reasoning (QR) courses like applied statistics instead of college algebra (CA). When studies report gains in gateway math completion under corequisites, they are often measuring the combined effect of both reforms.
Recent research, including our new Kentucky study, has started to disentangle these questions. Emerging evidence suggests that the efficacy of corequisite remediation is far from a foregone conclusion. These findings have important implications for how heavily we should invest in a particular model of corequisite remediation.
What the prior evidence shows
When Florida made remediation optional for most of its academically unprepared students, gateway course completion rates rose, hinting that gains attributed to corequisites elsewhere may simply reflect the removal of barriers rather than the addition of effective support.
The handful of studies that compare corequisite remediation directly to no remediation at all reach mixed conclusions. A Tennessee study found that corequisite remediation in math and English had no detectable advantage over direct enrollment without remediation. In fact, for students in the college algebra pathway, students placed into corequisite support were 16 percentage points less likely to pass college algebra than similar students receiving no remedial support. A more recent Texas study reached a different conclusion: Students assigned to corequisite math were 12 percentage points more likely to pass college math within a year than students assigned to no remediation. The Texas study did not distinguish the types of math courses, so the degree to which the effect was driven by math pathway reforms is unclear. That is, students may be completing gateway math at higher rates partly because they were taking different, less demanding courses, not because the corequisite support made them more proficient.
New evidence from Kentucky
Our recent study of the Kentucky Community and Technical College System adds to this mixed picture. Kentucky’s placement policy has two distinctive features: It divides students into three tiers of college readiness and offers a hybrid “prerequisite plus corequisite” sequence for the least prepared students. Because college readiness is a continuum, Kentucky’s three-tier placement policy reflects a more realistic view of college readiness than the two-tier policies studied in prior research.
Kentucky established benchmarks for English, the CA math pathway, and the QR math pathway. For English and the CA math pathway, top-tier students enroll directly in college English and college algebra, middle-tier students receive corequisite support, and bottom-tier students must complete a prerequisite course before taking corequisite courses. The QR math pathway has lower remediation requirements: Middle-tier students can enroll directly in QR math courses, and bottom-tier students can take those courses with corequisite support without completing any prerequisites. The remedial supports for each pathway and college readiness tier are shown in Table 1 below.
Because students were assigned to remediation based on benchmark cutoffs, we estimate causal effects using a regression discontinuity design. This method takes advantage of the fact that students who score just below a benchmark, and are therefore assigned to one form of remediation, are on average very similar to students who score just above it. Comparing outcomes for these two groups isolates the effect of the intervention from underlying student differences.
Tracking approximately 43,000 first-time degree-seeking freshmen who entered between 2019 and 2024, we found a mixed picture.
In English, corequisite support showed genuine promise. As shown in Figure 1, middle-tier students were about 5 percentage points more likely to pass college English within their first year than similar students who were not assigned to any remedial support. We also found that the benefits were particularly strong for male and part-time students (see study). Adding prerequisites to corequisite support for the bottom-tier group of students, however, was counterproductive: It reduced first-year college English enrollment by 6 percentage points.
In math, the story was more complicated. As Figure 2 shows, we found no overall change in first-year completion of gateway math. Neither corequisite support for middle-tier students nor an added prerequisite for bottom-tier students improved college algebra passing rates. For QR math courses, by comparison, corequisite placement increased completion by two percentage points. We also found that, among women, the gain was more prominent at almost 5 percentage points (see study). But these gains appear to stem largely from middle- and bottom-tier students shifting from CA to QR math courses.
Policy implications
Findings from Kentucky reflect the complexity of choices that many college students face. These findings carry several implications for the ongoing national conversation about remedial education.
First, while corequisite remediation is better than the old prerequisite approach, that is a low bar. When compared to no remedial support, corequisite instruction shows small benefits in English and QR math, but not in college algebra.
Second, much of what has been reported as a “corequisite effect” in math appears to be a math pathway effect. Students are completing gateway math at higher rates partly because they are taking non-college algebra math courses. That is not necessarily a bad outcome. If a student’s program does not require algebra, taking the appropriate course is sensible. But for students whose programs and future jobs require college algebra, we still lack an effective support strategy.
Third, adding prerequisites on top of corequisite support does not help the least prepared students. Delaying access to college-level coursework, even with good intentions, tends to hold students back rather than prepare them for future coursework.
We know what is harmful, but we have not figured out what is genuinely effective. Part of the answer may lie in design. Corequisite remediation is not a monolithic model, and studies from Colorado and Texas have linked design features such as support intensity and instructor assignment to gateway course-passing rates. These associations may vary by student race/ethnicity, subject, and level of precollege preparation. But much of this scholarship is descriptive, and most of it compares corequisite implementations to prerequisite remediation, making it difficult to tell whether the observed variation reflects differences in how much harm prerequisites cause or in how much help corequisites provide. Sorting that out is the next step.
Related Content
The Brookings Institution is committed to quality, independence, and impact.
We are supported by a diverse array of funders. In line with our values and policies, each Brookings publication represents the sole views of its author(s).
