Sensory sensitivities in children are found not only across a range of childhood disorders, but also within the general population. The current exploratory study examines the reliability and validity of a novel parent-report measure which assesses sensory-sensitivities in both typically developing and non-typically developing children. This 42-item Parent-completed Glasgow Sensory Questionnaire (GSQ-P) has been adapted by us from an existing adult tool (Glasgow Sensory Questionnaire), and measures children’s hyper-sensitivities (sensory overload leading to avoidance-behaviours) and hypo-sensitivities (sensory dampening leading to seeking-behaviours) across seven different sense domains (visual, auditory, gustatory, olfactory, tactile, vestibular, proprioception). We validated this novel measure on the parents of 601 English children 6–11 years. Both the long version (42-items GSQ-P) and an additional reduced version (24-item rGSQ-P) significantly associated with children’s anxiety, behavioural difficulties, and ability to empathise. As expected, sensory sensitivities were invariant across age and gender, but non-typically developing children had significantly elevated scores compared to typically developing peers (in both GSQ-P and rGSQ-P). We also provide insight into the structure of sensory sensitivities in children, showing for the first time that hyper sensitivities cluster by sense (e.g., tactile questions cluster together; visual questions cluster together) whilst hypo sensitivities cluster by behaviour (e.g., a cluster of seeking-behaviours irrespective of sense; a cluster of sensory dampening irrespective of sense). We offer both instruments (GSQ-P and rGSQ-P) as free reliable measures for better understanding children’s sensitivities, for use in different circumstances depending on focus.