In this paper, the concept of sustainability consciousness, an individual's experience and awareness of sustainable development, is introduced. Based on UNESCO's definition of sustainable development, a sustainability consciousness questionnaire (SCQ) is theoretically and empirically developed. Using the data of 638 respondents from Sweden aged 18-19 years old, the scale is developed in two versions. The long version (SCQ-L) can be used to measure individuals' environmental, social and economic knowingness, attitudes and behaviour (nine valid and reliable subscales), in addition to the second order constructs of sustainability knowingness, sustainability attitudes and sustainability behaviour, as well as the third order construct, sustainability consciousness. For the short version (SCQ-S) 27 items were identified that can be used to measure the second and third order constructs. Both versions of the scale present excellent psychometric quality. Possible applications of the questionnaire instruments in the context of evaluation of sustainability policies, practices and stakeholder engagement are discussed. KEYWORDS empirical validation of the sustainability consciousness questionnaire, questionnaire instrument, stakeholder engagement, Sustainability Consciousness, sustainable development, sustainable development policy, theoretical development of the construct of sustainability consciousness