It's ironic that, just as the U.S. poverty rate rises to its highest level in more than four decades, the Pell Grant program -- the most important source of federal aid for low-income students aspiring to a college education -- celebrates its 40th anniversary.There is good reason to celebrate the Pell Grant's huge impact on expanding college access. Named after the late Sen. Claiborne Pell, D-R.I., the program provides need-based assistance that has made it possible for 60 million students to pursue their dream of higher education, young people who otherwise would not have had that opportunity.According to the U.S. Education Department, the number of recipients is up 52 percent since 2008, to an expected 9.4 million in award year 2011-12, a direct result of the economic downturn and the growing ranks of students and families needing assistance.Despite a recent increase in the maximum value of the Pell Grant to $5,550 next year, the average grant now covers just 21 percent of the cost of attendance at a postsecondary institution. With recent changes that reduce student eligibility to 12 semesters from 18, tens of thousands of students will be left without enough financial support to complete their education.Why this erosion in value? We have seen an unfortunate shift by policymakers and institutions of higher education away from emphasizing need-based aid to ensure that college remains open to all students, regardless of their economic circumstances, and an accompanying move in favor of education tax credits and merit-based aid.The problem is that the populations historically underrepresented in higher education -- low-income, minority and first-generation students -- are the same populations that most depend on need-based assistance.Yes, it is important to balance the need to provide financial aid to large and growing numbers of underserved students with other considerations. We must ensure that this enormous investment of taxpayer resources is used efficiently and effectively, including providing incentives for students to complete college within a reasonable time frame.But increasing financial support is only half the story. Equally important is providing Pell Grant recipients with other types of support and guidance. Many of these students face multiple barriers -- academic, socio-economic, cultural, informational -- to postsecondary education, not just a lack of funds. Merely providing them with financial aid is not enough to get them through college.Education Department data show that, six years after beginning their undergraduate program, students who have received a Pell Grant and participated in TRIO Student Support Services -- another federal program that provides counseling, tutoring, mentoring and other guidance to underserved students -- have a higher rate of earning a baccalaureate degree (30.9 percent) than other low-income college students who received only a Pell Grant (21 percent).Poverty rates are rising and the U.S. has slipped to 16th in the percentage of college graduates among countries in the Organization for Economic Cooperation and Development. Federal and state policymakers and college leaders need to do everything possible to support and encourage students from all walks of life who aspire to a degree.Instead of shrinking that opportunity, we should work together to guarantee access to higher education by ensuring that rising tuition and student debt are held in check and that assistance -- financial aid and other types of proven support -- is focused more on those with the greatest need.After four decades, that would truly be cause for celebration.Arnold Mitchem is president of the Council for Opportunity in Education, which includes the Pell Institute for the Study of Opportunity in Education.