This dataset includes data from the Young and Well Towns (YAWT) Collaborative Research Centre (CRC) project. A randomised controlled trial was conducted that investigated the efficacy of an online recommendation service (Online Wellbeing Centre, OWC) for readily available mobile apps to improve wellbeing. Participants were adolescents and young adults (age 16 - 25) from Australia who were randomly assigned (1:1) to an intervention or control group. Participants in the intervention group received access to the OWC and the study platform, whereas participants in the control group only received access to the study platform. A range of psychological and behavioural measure before randomisation and 4 weeks after randomisation. In addition, participants were continuously monitored over the study period with regard to subjective mood, sleep, rest and energy. Data available includes Data completeness report, Variables codebook, and Data cleaning and augmentation procedures.