Dario Guerrero is one of those kids who defines the American Dream. In an essay for the Washington Post , Guerrero wrote about taking engineering classes at a local community college when he was still a high school junior nursing big career ambitions. But, because Guerrero’s parents brought him from Mexico to the U.S. without legal documentation when he was a little boy, it turned out to be a challenge to pay for the college education he wanted.

Unable to get financial aid to attend a state school, he sought out private colleges that might help him out. Fortunately for him, he was talented and lucky enough that one did, and it was Harvard.

That’s not a scenario that works out for most undocumented kids, no matter how hard they work. But a 2008 study suggests that even a small bit of financial support for these students can encourage college attendance. Writing in the Journal of Policy Analysis and Management, Neeraj Kaushal considered the effects of allowing undocumented students to receive in-state tuition rates at their state colleges and universities.

Kaushal writes that about 70,000 undocumented students graduate from high school each year. Since 2001, a number of states, starting with Texas and California, have started allowing many of them to pay in-state tuition. Looking at a sample of young Mexican immigrants who were statistically likely to be undocumented, Kaushal found that offering the lower tuition rates was associated with a 31 percent increase in college enrollment, a 37 percent increase in the portion with at least some college, and a 33 percent increase in the likelihood of having a college degree.

Despite the clear results of the tuition subsidy, the total numbers of the immigrant students benefitting from a college education were still small—overall, just 11.5 percent of the sample were enrolled in college, 13.7 percent had some college under their belts, and only 5.3 percent had a degree. Kaushal notes that a number of other factors may be in play, including the fact that many undocumented youth do not graduate from high school, the fear that applying for a tuition subsidy could lead to deportation, and the inability of some students to pay even the lower in-state rates.

“The broader policy issue is whether state governments should improve educational opportunities for undocumented immigrant youth, whose numbers have been growing in recent years,” Kaushal writes. “Without opportunities for college education, these undocumented youth may be pushed into an underground economy and remain isolated from the mainstream American society.”

In other words, Harvard can’t help every kid, but more can be done to help students like Dario Guerrero find a way forward.