This OSF page is dedicated to the Urban Rotterdam Project, an online longitudinal behavioral survey study including adolescents and young adults aged 10 to 25 years living in Rotterdam and surrounding areas with varying socio-economic backgrounds. In this study, data were collected every six months in the period of May 2020 until December 2023, resulting in eight waves of data collection. For the first three waves (May 2020, T1; November, 2020, T2; May 2021, T3), the project consisted of two major components: 1) a sub-project focusing on EUR (Erasmus University Rotterdam) students and 2) a sub-project focusing on adolescents living in the Rotterdam area. From the fourth wave onwards (December 2021, T4; May 2022, T5; December 2022, T6; May 2023, T7; December 2023, T8), both samples of adolescents and students were combined. At the first two waves, participants were asked to fill in daily questionnaires for two consecutive weeks, while from the third wave onwards data were collected in a single questionnaire. From wave 4 onwards, new participants were newly recruited and included at each wave. The larger project is expected to result in several research articles, that all answer different research questions. On this OSF page, you can find the following documents: 1) the raw questionnaires as presented to the participants at all waves (for T1-T3 separate for adolescents and students). Note that questionnaires were presented in Dutch to all adolescents, and that students could fill in the questionnaires in either Dutch or English (see files). 2) A detailed description of the questionnaires at all waves, including translations to English and references (see files). 3) Pre-registrations for the articles (see linked components).