The Harvard University Institute of Politics survey found that 43% of Americans aged 18 to 29 back the idea of building a border wall, while 53% opposed it.
Support differed significantly depending on political affiliation, with 70% of Republican millennials backing a wall, compared with 31% of Democrats who felt the same way. Among independents, 42% said they favor a wall.
Half of millennials describe themselves as political independents, according to a previous study by the Pew Research Center, and 40% identified themselves as independents who don't lean toward either party in the Harvard IOP poll.
Following the Paris terrorist attacks last month, a majority -- 60% -- a subset of young adults recontacted by Harvard -- backed sending U.S. ground troops to combat ISIS. Before the attacks, less than half -- 48% -- of millennials were on board with using ground forces to stop the terror group.
The findings are not much out of line with how Americans of all ages feel about putting boots on the ground. In a CNN/ORC poll conducted before the San Bernardino massacre, a majority of Americans -- 53% -- said the U.S. should send ground troops to combat ISIS.
In the Harvard poll, 20% of those questioned consider themselves "politically engaged and active" -- a 5 percentage point drop from a similar survey conducted in fall 2011. More than half -- 52% -- said they were not following the presidential race closely or at all.
Among potential Republican primary voters, the poll found Donald Trump receiving the most support of any candidate at 22%.
And while Hillary Clinton is ahead of Bernie Sanders in national polls of likely Democratic primary voters, the Vermont senator is the favorite of millennials; he leads Clinton 41% to 35% among that age group, Harvard found.
A majority of millennials surveyed say they'd ultimately prefer to see the Democrats win the White House in 2016 (56%).
The poll has a margin of sampling error of +/- 2.8 percentage points and 2,011 young people were surveyed from October 30 through November 9.