The development and use of learning trajectories is a body of research that has made enormous contributions to the field of mathematics education, offering insight into the teaching and learning of topics at all levels. Simultaneously, the work of building learning trajectories can benefit from explicitly adopting an anti-deficit stance, incorporating ways to center student voices from an asset-based perspective. In this paper I propose two related constructs to support this work: decentering and second-order models. In decentering, researchers work to set aside their own knowledge to understand students' reasoning as viable. This can support models of student mathematics that position student thinking as rational, powerful, and productive. I provide one example of the work of decentering and discuss ways to build learning trajectories that emphasize students' strengths and competencies. [For the complete proceedings, see ED630210.]