The Theory of Planned Behaviour (TPB) has been successfully employed to investigate the role of gambling-related beliefs in the maintenance of gambling behaviour. However, there is a lack of research that examines the temporal relationships between the TPB predictor variables and gambling behaviour. Thus, the current study examines the utility of expectancies, normative beliefs, perceived behaviour control and gambling intentions in predicting gambling frequency, as assessed 12 months later. In addition, these gambling-related beliefs were reassessed at the 12-month follow-up survey to examine their stability and relationships with gambling behaviour. A total of 805 Australian adults, recruited via an online research panel, completed the baseline and follow-up online survey. Consistent with expectations, gambling-related beliefs explained gambling intentions and intentions predicted Wave 2 gambling frequency, after controlling Wave 1 gambling frequency. In relation to the stability of gambling-related beliefs, the Wave 2 measures explained additional variance in the Wave 2 gambling behaviour, although the type of beliefs associated with Wave 2 gambling frequency and problem gambling severity differed. These findings provide support for the notion that the perceived benefits of gambling and beliefs in skill are important areas to target in preventative and problem gambling initiatives.