The focus of the article is the process educators use to interpret data to turn it into usable knowledge (Honig & Coburn, 2008) while engaging in a continuous improvement process. The authors examine the types of evidence educators draw upon, its perceived relevance, and the social context in which the evidence is examined. Evidence includes data related to student or school outputs (e.g., passing rates), inputs (e.g., student demographic information), school processes (e.g., data on program implementation) and perceptions (e.g., surveys) (Marsh, 2012). Previous research also indicates that educators draw on evidence substitutes--anecdotal information, experience, intuition, ideological preference, and customary practice (Bryk & Gomez, 2008; Dorman & Binnewies, 2015; Ingram, Louis, & Schroeder, 2004). Considering this diversity of evidence enabled the authors to examine how teacher-led implementation teams come to shared conclusions about what they are learning about their improvement efforts. The following research questions are asked: (1) How are educators learning about and using data for the improvement of a school-wide reform; (2) What types of evidence are they citing to make claims about what they are learning; and (3) What are the barriers educators face as they learn how to apply data to make claims about what they are learning? Two tables are appended.