This paper explores the reasoning processes expert teachers use when reading and responding to elementary students' writing. We report findings from a qualitative multi-case study drawing on "think-aloud" interview data from seventeen participants as they read and responded to narrative, informational, and opinion/argumentative drafts. Findings indicate the teachers looked for the logic in student drafts, compared the drafts to an internalized "expected text," responded to meaning before mechanics, framed their responses within an iterative process, and prioritized what they chose to respond to. The findings suggest three aspects of teacher reasoning that extend the current literature on effective reading and responding: (1) an appreciative stance grounded in a view of children as authors; (2) comparison to complex multi-faceted expected texts; and (3) reasoning in terms of iterative response cycles. By unpacking expert teacher reasoning, this study provides insight into what novice teachers must learn in order to formulate effective responses and points to the importance of future research into how to support this learning.