For the HEBECO Study documentation, pre-registered protocols and supplementary materials for published manuscripts, please see the information in the folder section. We invite research collaborators interested to analyse the HEBECO data. Please contact: Dr Aleksandra Herbec (a.herbec@ucl.ac.uk). Background: The COVID-19 pandemic has resulted in the introduction of a number of social distancing measures that may impact on a number of health related behaviours – some may act as catalysts to positive behaviour change (e.g. quitting smoking) but some may impede positive health behaviours and lead to sustaining or an increase in risky or unhealthy behaviours. Understanding these processes is paramount for us to deliver or create appropriate interventions.Furthermore, due to social distancing measures, the face-to-face behaviour change support (such as individual or group support from smoking cessation or alcohol abuse) are currently closed. In such context digital and remote interventions are the most feasible interventions. This project utilises logitudinal design to investigate changes in health behaviours during the COVID-19 and the theoretically factors contributing them. In the first phase, the present study applies longitudinal survey design and behavioural frameworks (Theoretical Domains Framework and COM-B, Michie et al, 2014) to inform data collection and analyses of (i) changes in behaviours related to physical activity, tobacco use (i.e. smoking, quitting, harm reduction), nicotine use (e.g. vaping, use of nicotine replacement therapy) and alcohol use during the COVID-19 pandemic, and (ii) needs and preferences for digital or remote behaviour change interventions. The project has been approved by a UCL Research Ethics Committee (CEHP/2020/579_. Data is collected through REDcap (https://projectredcap.org/). Identifiable data is stored on UCL Data Safe Haven (https://www.ucl.ac.uk/isd/services/file-storage-sharing/data-safe-haven-dsh).