Here are a couple of very interesting and extensive articles on graduation rates and the need to promote graduation for all students. The first article talks mostly about the graduation gap between the upper 2/3 of high school students and the lower 1/3, made up mostly of urban, low-income African American and Latino students. The other article is from the Governor’s Guide to Dropout Prevention and Recovery.
http://www.nga.org/Files/pdf/0910ACHIEVINGGRADUATION.PDF
http://www.ppionline.org/ppi_ci.cfm?knlgAreaID=450020&subsecID=900201&contentID=254746