The global agenda to move societies towards a more sustainable course of development also affects the lives of older people in our ageing populations. Therefore, it is important to understand the drivers, intentions and behaviours concerning sustainability among older adults. The aim of this study is to translate and cross-culturally validate an existing instrument (SustainABLE-16 Questionnaire), developed in the Netherlands, which measures how older people view the theme of environmental sustainability in their daily lives, for use in Romania, Poland, North Macedonia and Israel. The SustainABLE-16 covers three domains: 1) Pro-environmental behaviours; 2) Financial position; and 3) Beliefs. The scale was translated in Romanian, Polish, Macedonian, Albanian and Hebrew. Its 16 items were appraised for relevance by older people and experts in the field. A total of 2299 older people, including the original Dutch respondents, were included for the assessment of the level of measurement invariance across six languages, spoken in five countries. As the initial validation of the SustainABLE-16 did not meet internationally-recognised fit requirements, the shorter SustainABLE-8 was validated instead. This instrument proved valid for use in all participating countries (configural validity). Subsequently, increasingly constrained structural equation models were applied to test their fit with the data, ensuring that the fit did not deteriorate. The test results of measurement invariance across the countries indicated that items were stable, achieving partial scalar invariance, with five items demonstrating full scalar invariance. The shorter SustainABLE-8 functions uniformly across all language groups and can, therefore, be used to evaluate sustainable practices among older people. A better understanding of the drivers and practices among older citizens across Europe could, in turn, feed into more fitting public policies on sustainability in the built environment.