Artificial lighting is a significant threat to biodiversity. Although efforts to reduce lighting are crucial for species’ conservation efforts, management is challenging because light at night is integral to modern society and light use is increasing with population and economic growth. The development and evaluation of appropriate light management strategies will require positive public support, and a comprehensive understanding of public engagement with light pollution. This is the first study to examine public engagement with reducing light at night for the protection of a threatened species. A community campaign to reduce artificial light use was initiated in 2008 to protect marine turtles at a globally significant nesting beach. Semi-structured questionnaires assessed community engagement with light-glow reduction, using an existing theoretical constraints framework. Despite high levels of cognitive and affective engagement (knowledge and concern), behavioural engagement (action) with light reduction in this community was limited. Community perceptions of light reduction were dominated by ‘uncertainty and scepticism’ and ‘externalizing responsibility/blame’, implying that behavioural engagement in this community may be increased by addressing these widely-held perceptions using modified campaign materials and/or strategic legislation. Further refinement of the theoretical constraints framework would better guide future empirical and conceptual research to improve understanding of public engagement with critical environmental issues.