Postsecondary institutions are redesigning the ways in which they offer remedial courses to support students' progress and eventual success in college more effectively A corequisite approach places students assessed as marginally remedial directly into college-level courses but provides them with additional academic support. The rationale is that without the delay of having to take prerequisite remedial courses, students are more likely to build and sustain academic momentum, accumulate college credits more quickly without sacrificing learning quality and are therefore more likely to graduate in a shorter time frame. Relying on a state corequisite pilot program and state-level standardized test cutoff scores, the study uses student-level data and the Difference-in-Difference with moderator method to compare short-term college outcomes between corequisite students and traditional remedial students as well as college-level students. Findings indicate that corequisite math students at four-year institutions seemed to have benefited the most from the redesigned approach as they consistently outperformed their traditional remedial peers post-policy and reduced outcome gaps with college-level students or even outperformed them on some measures related to academic standing, college credit accumulation and first-year persistence. Corequisite English students seemed to have only gained some advantages over increased GPA with effects of much less magnitude and consistency. Corequisite students of both subjects at two-year institutions seemed to have garnered little to no progress overtime with their corequisite experience. In addition, both White and minority corequisite math students at four-year institutions performed equally well with minority students being able to reduce gaps on some outcome measures. The similarly distributed benefit of the corequisite program among four-year math students wasn't observed among four-year English students nor among students of both subjects at two-year institutions. At two-year institutions, the advantage of participating in the corequisite program seemed to have mainly been absorbed by White students who showed stronger performance over time. Gender outcome gap continued to exist among all samples with female students still being the high achievers except for the subject of math at four-year institutions where male corequisite math students seemed to have greatly reduced the outcome gap in terms of college credits accumulation. While the gender outcome gap reduction isn't as frequently seen as the racial outcome gap reduction, it is still a welcome sign. Findings from the study on the main effect and subgroup analysis by race align with existing evidence. Findings on subgroup analysis by gender adds to the current pool of evidence. The study constructs two control groups for the corequisite students to have extended evaluation of the validity of the treatment effect estimates. Post-estimation analysis unpacks the mechanism that drives observed treatment effects. Significant and positive treatment effects are only counted as findings if they are validated via post-estimation analysis and are consistent across both sets of comparisons. Inclusion of two analytical pathways of intent-to-treat and average-treatment-of-the-treated presents potential effect of the corequisite policy overall and the effect on the treated per se. Results support the on-going remediation reform effort at both the institutional and state level to expand the corequisite pool of students beyond just the marginally remedial so that more students may progress to the finish line faster. The study, however, cautions against more dramatic reform practices, such as eliminating remedial courses completely or implementing a new holistic assessment metric. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]