Introduction: Tobacco presence in outdoor children’s playgrounds is concerning not only because it leads to secondhand smoke (SHS) exposure, but also cigarette butt pollution and tobacco normalization. Objectives: This study aimed to assess SHS exposure in children’s playgrounds, according to area-level socioeconomic status (SES), smoke-free regulations, national smoking prevalence, and SHS exposure prevalence in playgrounds (2017–2018). Methods: We monitored vapor-phase nicotine concentration and tobacco-related variables in 20 different playgrounds in 11 European countries (n = 220 measurements) from March 2017 to April 2018. Playgrounds were selected according to area-level SES. Data on the number of people smoking, and cigarette butts inside the playground and on playground surroundings (