Abstract The functional properties of the visual system are most sensitive to disruptions of normal vision during developmental ‘critical periods’. Interestingly, the critical periods for several functional properties, such as ocular dominance and acuity, overlap during development. Abnormal vision during these overlapping critical periods, because of cataracts or misalignment of the two eyes for example, is the cause of amblyopia. Amblyopia is a prevalent visual disorder in children and can present with any of several visual problems including lower visual acuity and impaired depth perception. Yet, how depth perception is affected by abnormal vision has remained elusive. In the proposed research, we investigate the circuit basis for the development and plasticity of depth perception in the mouse. The development of stereoscopic vision is much slower than other characteristics of vision and relies on complex properties of binocular disparity. Disparity between the eyes is what produces the perception of depth. We will characterize multiple dimensions of its development and plasticity by taking advantage of a natural depth discrimination task that depends on binocular vision. Over this same period, we will measure with two-photon microscopy how complex disparity properties are refined in the visual cortex and area LM (a secondary binocular visual area), as well as how and when they are sensitive to abnormal vision. Understanding the properties of binocular depth perception and the development of those properties will provide a foundation for developing therapeutic approaches to treat developmental visual disorders such as amblyopia that cause stereovision deficits.