Over a decade and a half, community college enrollment for part-time students who are younger than 18 has more than doubled, jumping from 287,000 in 2001, to more than 635,000 by 2015 -- an increase of 122 percent. By contrast, total enrollment in community colleges only increased by 14 percent over the same period. Of particular note, this population continued to increase between 2011 and 2015 by 35 percent, while total enrollment declined by 11 percent. While the data do not allow us to determine whether these students have graduated from high school, there is strong evidence that these students are predominantly enrolled in college classes while still enrolled in high school. Data from a separate U.S. Education Department research study indicated that in the 2010-11 academic year, there were more than 873,000 students enrolled in formal community college dual-enrollment programs, and another 106,000 high school students taking community college credits outside of dual-enrollment programs. This estimate of 980,000 high school students was based on the full academic year, not just fall enrollment. However, if the trend represented by the fall enrollment data are projected onto the 980,000 students enrolled in 2010-11 academic year, then approximately 1.3 million high school students took community college credits during the 2015-16 academic year.