As the 21st century's first decade draws to a close, America's public school students are participating in online academic classes in increasingly large numbers. More than one million K-12 public school students took online courses in the 2007-2008 school year, according to an estimate in a recent Sloan Consortium survey. This represents a 47 percent increase from 2005 to 2007 alone. With such rapid growth, many educators and state decision-makers have grown wary and want to know what the research says about online learning: They want to know if it works. Available research indicates that it does. This report outlines recent research that can help educators and state decision-makers understand the benefits of online learning. One clear measure of the benefits--and perhaps the most important--is increased "student learning". Another is increased "student access" to high-quality courses. [A combined directory of References, Research and Studies Related to Online Learning is provided.]