Many urban districts have adopted interim assessments in recent years as a supplement to annual testing. Possible purposes for such tests include monitoring and assisting student progress, aligning the curriculum, and practicing for state exams, but little is known about how effectively real systems advance these purposes. The Providence Public School District (PPSD) implemented a system of quarterly assessments at every grade starting in 2004 and discontinued them in 2007. During the implementation period, authors interviewed district officials about what they were trying to accomplish, and teachers and other school personnel about their experiences with the assessments and their use of the results. Evidence of effectiveness as well as limitations were found. Uncertainty about the magnitude of positive impacts raised questions about the net value of the assessments given their considerable costs to districts, teachers, and students. The authors conclude that interim assessments are costly, and costs increase if the desired effects on student achievement require significant investments in professional development of teachers. Sound policy, therefore, should be carefully designed and evaluated. Two appendixes are included: (1) Interview Protocol; and (2) Findings from Interviews and Survey. (Contains 3 tables.)