The MAP-19 Study was initiated in 2020 and investigated the mental health sequelae tied to the COVID-19 pandemic and its mitigation protocols, in addition to factors predicting adherence to viral mitigation protocols and preventive health behaviours (e.g., vaccination uptake). Participants included over 10,000 adults from Norway, followed up with 10 repeated assessment waves over 3 years. A subsample of over 2,750 participants was recruited for the Daily Diary sub-study, where each participant completed daily assessments over 40 days (yielding more than 108,000 observations) to investigate the granular mechanisms and contextual stressors related to a diverse range of mental and physical health problems experienced during the pandemic. The MAP-19 study includes an extensive and comprehensive measurement of mental health outcomes, physical health outcomes, COVID-19 infection and related variables, contextual variables, sociodemographic circumstances, as well as risk factors and associated psychosocial mechanisms.