--- - |2 An increasing number of scientific publications have provided data from different countries suggesting subjective well‐being (SWB) continuously decreases during adolescence. A review of these publications reveals authors have used dissimilar scales in diverse countries. Using data from the international Children's Worlds project (N = 48,040), involving 15 countries, a comparative analysis was performed to determine how mean scores evolve with different SWB scales from the age of 8 onwards. The results support the hypothesis that the tendency of SWB to decrease with age starts at around 10 years of age in most countries, while also confirming that different psychometric scales display different levels of sensitivity to diverse sociocultural contexts and more than one should be used in any research on children and adolescents’ SWB. - Child Development, EarlyView.