Teachers' instructional practice is pedagogically vulnerable when not anchored within detailed and comprehensive observation and understanding of students' immediate responses during instruction. Professional noticing ability, then, is central to, and integrated within, teachers' ability to provide instruction appropriately adapted to students' immediate needs. This article explicates a model of expert noticing for literacy instruction and relates this model to the characteristics of microadaptive teaching decisions. Characteristics, for example, that distinguish expert from less expert noticing during literacy instruction include detailed hypothesizing, breadth and depth of elaboration, observation of learners' metacognitive behavior, and identification of pivotal events. Teacher noticing ability is generally not related to years of experience, but can be learned through participation in sustained, multilevel professional development with an explicit focus on noticing ability. This complex learning integrates teachers' pedagogical and content knowledge with observation of student behaviors, and supports teachers' learning from practice.