Institutional environments, comprising regulative pressures by funding agencies and journal publishers, and institutional resources, including the availabilities of data repositories and standards for metadata, function as important determinants in scientists’ data-sharing norms, attitudes and behaviours. This research investigates how these functions influence biological scientists’ data-sharing norms and how the data-sharing norms influence their data-sharing behaviours mediated by attitudes towards data sharing. The research model was developed based on the integration of institutional theory and theory of planned behaviour. The proposed research model was validated based on a total of 608 responses from a national survey conducted in the USA. The Partial Least Squares (PLS) was employed to analyse the survey data. Results show how institutional pressures by funding agencies and journals and the availabilities of data repository and metadata standards all have significant influences on data-sharing norms, which have significant influences on data-sharing behaviours, as mediated by attitudes towards data sharing.