Mac Iver, Martha A. and Douglas J. Mac Iver. Baltimore Education Research Consortium, Baltimore, Md. April 2011.A study of two first‐time ninth grade cohorts in Baltimore City Schools, followed forward to their on‐time graduation year and one year beyond, found that increasing ninth grade attendance and course passing rates is the most important lever for increasing the graduation rate. The probability of graduation increases steadily as ninth grade attendance rates increase. More than eight in 10 who attended school at least 95 percent of the time in ninth grade went on to graduate. By contrast, the graduation rate was lower than 20 percent for those ninth graders who attended less than 70 percent of the time.