This article addresses conflicting statements about the impact of accountability policies in which some argue that testing undermines good teaching, while others claim that it stimulates improvement. The authors begin with the assumption that it is important to explore implementers' cognitive perspectives in order to understand a policy's effects. Using a sensemaking perspective, they examine teachers' responses to accountability in three high schools selected because they were deemed to have a strong teacher culture that supported quality education. The schools were located in states with diverse histories of accountability legislation, but in districts with well-established local accountability policies. Findings suggested that sensemaking activity occurred in all three schools and was associated with teachers' interpretation of accountability policies and with their efforts to change classroom practice to be consistent with accountability policies. Active efforts by district-level administrators to mediate sensemaking affected teachers' attitudes toward accountability policies and standards-driven reform. (Contains 1 table and 7 notes.)