The macaque cerebral cortex contains a set of areas that seem to be specialised to process information about visual motion. Prime among these is area MT (V5), where neurons are exquisitely sensitive to visual motion. Signals transmitted by MT neurons have been been causally linked to behavioral motion sensitivity. We studied the development of visual motion sensitivity using behavioural methods in pigtail macaque monkeys by measuring the animals’ sensitivity to coherent visual motion imbedded in visually-noisy dynamic random dot displays. We also measured motion sensitivity in adult macaques made amblyopic by rearing either through optical defocus or surgical deviation of one eye, using methods detailed by El-Shamayleh et al. (2010). We studied neuronal responses to visual motion in the same and other acutely prepared normal and amblyopic macaques anesthetized with sufentanil (4-20 μg/kg/h, i.v.), paralysed with vecuronium (0.1 mg/ml/h) and artificially ventilated. Anesthesia and physiological status were monitored as detailed by Movshon et al. (2005) and El-Shamayleh et al (2010). Behavioural motion sensitivity develops over a relatively long time course, extending well past the first year of life. During this time, coherence sensitivity increases, particularly to slow-moving stimuli. Amblyopia alters the course of development, reducing animals’ sensitivity to motion viewed through the amblyopic eye, both overall and selectively at low speeds, and produces a specific deficit in the temporal integration of motion signals. Physiological measurements in MT show that neuronal responses mature in sensitivity and selectivity over a relatively shorter time course than behaviour, suggesting that the early phase of motion sensitivity development may depend on neuronal signals in MT but that later development may not. Amblyopia affects the motion sensitivity of MT neurons with a pattern that in most respects resembles the change seen behaviourally, but some features of amblyopic motion vision ar enot explained by changes in MT and seem to depend on downstream processing. The pattern of development and plasticity of neurons in MT suggest that these neurons occupy a central place in a set of motion sensitive mechanisms. The data suggest that the process of visual development involves not only the well known changes that take place in primary visual cortex, but also engages a cascade of developmental processes in downstream cortical areas.