The current study describes and tests a new momentary model of victimisation worry, based on data collected from a smartphone app. We assess whether a momentary model provides further insight into the situated nature of fear of crime and risk perception. Data were collected from a sample of 72 young adults living in Southeast Queensland, Australia who completed momentary surveys on fear of crime that were administered on their mobile devices. Results suggest that constructs contained in our proposed momentary model of victimisation worry fit the data appropriately and that associations between dimensions of victimisation worry are all statistically significant based on their expected directions (i.e. increased perceptions of victimisation risk in the immediate area significantly predicts increased momentary worry about crime). We conclude with a discussion of the theoretical and practical implications of our findings, limitations of the current study, and direction for future research.