We hear about schools that have successfully useddata to make gains in student achievement. What weoften don't hear about are the nuances of the work. How did school leaders initiate the work? How didthey overcome the barriers? Beyond increases instudent test scores, what does data use look likewhen it is working? What happens in effective datameetings? What do teachers and leaders in theseschools talk about? How are connections made toinstruction?Using a case study approach to examine two urbanelementary schools with increases in studentachievement that outpaced district averages, thiswork describes the practices of teachers and leadersin these schools. Retrospective interviewing allowedfor an exploration of factors that had supported thedevelopment of successful practices. Cross-casecomparisons reveal that data use facilitatedcommunication, collaboration and instructionalchanges. Overall, the case studies providedescriptions of how two schools evolved from datareporting for accountability purposes to developcultures of data use that supported improvedinstruction and student achievement.