This chapters reviews the concepts of sensory integration and the disturbances in perception commonly seen in young children. The point of departure is the work of Jean Ayres, who described sensory difficulties in children several decades ago. She identified a number of sensory channels, including the vestibular and the proprioceptive systems, in addition to visual, auditory, olfactory, tactile and gustatory channels. The patterns of hyper-sensitivity to sensory stimuli, or its opposite, under-registration of stimuli are described as well as mixed patterns. These issues are very relevant in infant mental health, in understanding the problems of young children and school children at school. The main regulatory disturbances are described, together with strategies for intervention in the home and in the classroom. These include strategies to meet the individual needs of each child, be it of stimulation or of reduction in stimulation. We also describe relaxation and calming strategies as well as how to help the child regulate their sensory input with the help of caregivers.