Using a unique dataset of 227 convicted UK-based terrorists, this report fills a large gap in the existing literature. Using descriptive statistics, we first outline the degree to which various online activities related to radicalisation were present within the sample. The results illustrate the variance in behaviours often attributed to ‘online radicalisation’. Second, we conducted a smallest-space analysis to illustrate two clusters of commonly co-occurring behaviours that delineate behaviours from those directly associated with attack planning. Third, we conduct a series of bivariate and multivariate analyses to question whether those who interact virtually with like-minded individuals or learn online, exhibit markedly different experiences (e.g. radicalisation, event preparation, attack outcomes) than those who do not.