In a guest post, Brian T. Prescott, director of policy research for the Western Interstate Commission for Higher Education, known as WICHE, describes the implications of projected demographic shifts for admissions officers and college counselors.

The Western Interstate Commission for Higher Education is proud to have been producing projections of high-school graduates for over 30 years. Known as Knocking at the College Door, the series is scheduled to release its next edition this winter. These data provide stakeholders with important information about the future size and composition of the cohort that each year sits on the precipice of enrolling in college (or of joining the work force).

Broken down by state, projections of the overall size of the graduating class are crucial information for how states, local school districts, and others plan for future capacity needs. States expecting to see rapid growth face the challenges of accommodating growing demand; states looking forward to substantial declines have a different set of issues to address, including how to attract more students from elsewhere or whether to reconfigure the various roles and missions of its existing public institutions.

Much of the interest in our projections, especially from the news media, has focused on the size of the pool of graduates—and what it means for students’ odds of being admitted to the colleges of their choice. This preoccupation makes sense in a culture that prizes elite institutions and where there is a concentration of resources devoted to sorting students for admission into them. For a long time this tendency was fed by a constantly swelling pool of graduates.

This era of reliable growth is nearing an end, especially in the Northeast and the Midwest. Institutions will be faced with a new reality in which it is more difficult to find and attract students who meet their particular criteria for “fit,” which more than ever will include a desirable financial profile.

Meanwhile, the bigger story embedded in our projections is how rapidly the racial and ethnic composition of graduating classes is diversifying. Within a decade we anticipate that nearly half of public-high-school graduates nationwide will be students of color, and all states will confront this escalating diversification, to varying degrees. The fastest-growing segments of the population reaching traditional college age come from underrepresented racial and ethnic groups, especially Hispanic students, which at the national level are filling in the gaps left by a shrinking number of white students.

Unfortunately, we have struggled to serve such students as well as we serve their white peers, accounting for the achievement gaps that have proved so stubbornly persistent. As one indicator, underrepresented-minority students have earned an associate’s degree or better at a rate nearly one-quarter lower than white students.

Inadequate preparation remains a major barrier to improvement, and even before the onset of the economic collapse we are still weathering, the median income of students of color who attended public four-year institutions was less than half that of their white peers. Minority students attending public two-year colleges were even less well off financially.

This is happening at a time when pressure on higher-education institutions (and the policy structure that supports them) has never been higher. For a long time, policy debates over educational opportunity were framed primarily in terms of social justice and of equality. But more than ever before, the president, influential foundations, and many states recognize the unbreakable relationship between our society’s economic prosperity and security on the one hand and our ability to raise educational-attainment levels on the other.

If our projections–and those of many other prognosticators–are right, we have no choice but to enable underrepresented populations to achieve meaningful postsecondary credentials in far greater numbers.

That means we must confront preparation gaps by redesigning remediation and by better aligning secondary and postsecondary standards. We must also ensure that scarce resources are distributed where they will have the greatest impact on students’ choices about whether or not to enroll and on their subsequent academic progress. And it means we must attend to the needs of adult learners, not just the shrinking share of college students who enroll directly from high school (who are the focus of the commission’s projections).

In response to those challenges, measures of success in admissions and college counseling should emphasize how well practitioners are serving underrepresented populations in terms of both accessing postsecondary opportunities and making the most of them. Admissions officials and college counselors occupy an essential space at the intersection of educational opportunity, helping students expand their notions of what is possible, prepare and plan for the academic rigor and financial commitment of college, choose from among their options, and guide them onward through success in college.

The more they engage in that work with those who need it most, the better.

Mr. Prescott will discuss preliminary figures from the commission’s forthcoming report at the National Association for College Admission Counseling’s annual conference, in Denver, on Thursday afternoon.