The social plasticity hypothesis proposes that social attunement, i.e., the adaptation to and harmonization with one's environment, plays a crucial role in the risk for developing alcohol use disorders (AUDs) during adolescence, whereas in adulthood it paradoxically may make individuals more sensitive to the social pull to reduce drinking. This study aimed to develop a valid measure of social attunement: the social attunement questionnaire (SAQ). A total of 26-items were developed and the questionnaire was completed by 576 Dutch mid to late adolescents and adults over three rounds of online data collection. Using exploratory factor analysis in part of the sample (N = 373), the final questionnaire was reduced to two subscales with a total of 11 items. This structure was confirmed using confirmatory factor analysis in the second part of the sample (N = 203). Results showed that the SAQ has acceptable internal consistency, good measurement invariance to gender, and subscales assessing both cognitive as well as behavioural components of social attunement. In line with expectations on alcohol use settings, SAQ scores were not associated directly with alcohol use, but they were predictive of alcohol use when taking into account the interaction between perceived peer drinking and age. The SAQ appears suitable for the assessment of social attunement in (young) adult men and women, particularly assessing the role of social attunement in alcohol use settings. Further research is needed to confirm the utility of the SAQ in older adults and a broader variety of social settings.