ABSTRACT Physical literacy relates to an individual’s capacity to live a physically active and healthy lifestyle across the lifespan. Our understanding of physical literacy as a lifelong journey is hindered by a lack of valid measurement for adult populations. In response, we created a measure of physical literacy applicable to adults. A sample of 1180 adults answered a series of existing questionnaires assessing aspects of physical literacy. Using exploratory and confirmatory factor analysis techniques, we reduced the items to a 23-item six factor model, which had good fit to the data in both the exploratory analysis (χ2 (130) = 254.770, p < 0.001; TLI = 0.965; RMSEA = 0.040 (95% CI: 0.031, 0.049)) and confirmatory analysis (χ2 ;(130) = 252.005, p < 0.001; TLI = 0.957; RMSEA = 0.046 (95% CI: 0.036, 0.056)). The resulting subjective measure, the Physical Literacy in Adults Scale (PLAS), is a single psychometric measure applicable to adults aged 18–75 years. The PLAS covers four domains (physical, psychological, social and cognitive) of physical literacy to provide a holistic physical literacy outcome. The PLAS represents an appropriate way to assess adult physical literacy, providing an important first step in understanding physical literacy as a lifelong journey.