Carol Mason’s laboratory investigates visual system development, namely the cellular and molecular features of axon guidance, axon-target interactions and cell specification during patterning of the circuit for binocular vision. Her work on the visual system, and previously on the cerebellum, utilizes a suite of traditional and novel pathway tracing, correlated light and electron microscopic analysis, live imaging, culture assays and gene profiling. Over the past two decades, her laboratory has revealed a molecular program of transcription and axon guidance factors that specify the ipsilateral and contralateral retinal ganglion cell (RGC) pathways through the optic chiasm and to thalamic targets in the mouse brain. They have identified retinal axon-growth cone-guidance receptor systems that direct these two projections, transcription factors that regulate ipsilateral and contralateral RGC subtype identity, and the pre-target axon organization and developmental refinement of the retinogeniculate pathway. The laboratory also interrogates how axon targeting and cell specification go awry in the albino visual system, in which the lack of melanin leads to a reduction of the ipsilateral projection. For her work on the developing visual system, Mason was a co-recipient of the 2016 Antonio Champalimaud Vision award.