In the spring of 1995, the Chicago Public School system, the nation's third largest and, arguably, one of the most troubled, made national headlines when it was taken over by Mayor Richard M. Daley, then starting his third term and the most popular mayor since his father, Richard J. Daley, held the office for 21 years. By far the biggest reform introduced by Chicago Mayor Richard J. Daley and Paul Vallas, chief executive officer of the Chicago Public Schools from 1995 to 2001, was the education equivalent of "just say no," ending the practice of social promotion. The new policy required Chicago's lowest-performing third-, sixth-, and eighth-grade public school students to attend summer school and possibly repeat a grade at least once if they did not meet minimum reading and math test-score cutoffs on the Iowa Tests of Basic Skills (ITBS). It was an ambitious accountability agenda, and in the years that followed the policy's implementation, test scores among Chicago's lowest-achieving students rose, particularly in the upper grades, while the proportion of schools with extremely low performance fell. President Bill Clinton visited a Chicago school in 1997, proclaiming that he wants what is happening in Chicago to happen all over America. Since 1997, the policy has resulted in thousands of Chicago's elementary students being required to go to summer school and being held back every year. One reason for the popularity of the retention policy in Chicago--aside from the advantages of having a popular mayor to promote it--was the strong and relatively steady improvement in the Chicago schools. However, the policy was hit in April by two studies from the Consortium on Chicago School Research (CCSR), a nonprofit group affiliated with the University of Chicago. The studies suggested, with seeming definitiveness, that ending social promotion was ineffective, at best, and possibly destructive. The Chicago Board of Education, responding to the new CCSR reports, immediately modified its student retention program by dropping math scores as a consideration in retention decisions. In this article, the author discusses how Chicago changed--but ultimately saved--its controversial student retention program to end social promotion. (Contains 1 figure.)